Period of a solution in a trigonometric equation https://math.stackexchange.com/questions/1297742/period-of-a-solution-in-a-trigonometric-equation sin and cos have period 2π and tan has period π. When solving an equation, make sure to list all roots in a period. tanx =0 x = 0 in [0,π), i.e. x = kπ. tanx = 1 x= 4π ...1 Answer. Chandra S. Aug 14, 2015. cos x = - 1/2 = cos 2 π /3 ⇒ x = 2 π /3.cos( ) = x 1 = x sec( ) = 1 x tan( ) = y x cot( ) = x y FactsandProperties Domain Thedomainisallthevaluesof thatcanbe pluggedintothefunction. sin( ), canbeanyangleArccos. Arccosine, written as arccos or cos -1 (not to be confused with ), is the inverse cosine function. Both arccos and cos -1 are the same thing. Cosine only has an inverse on a restricted domain, 0 ≤ x ≤ π. In the figure below, the portion of the graph highlighted in red shows the portion of the graph of cos (x) that has an inverse.Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor.Cos x = -1. Cách giải phương trình cos x = a (*) B. Phương trình lượng giác thường gặp. Cách giải phương trình lượng giác cơ bản đưa ra phương pháp và các ví dụ cụ thể, giúp các bạn học sinh THPT ôn tập và củng cố kiến thức về dạng toán hàm số lượng giác 12. Tài liệu ...Mathematically, it is written as cos-1 (x) and is the inverse function of the trigonometric function cosine, cos(x). An important thing to note is that inverse cosine is not the reciprocal of cos x. There are 6 inverse trigonometric functions as sin-1 x, cos-1 x, tan-1 x, csc-1 x, sec-1 x, cot-1 x.Just as the distance between the origin and any point #(x,y)# on a circle must be the circle's radius, the sum of the squared values for #sin theta# and #cos theta# must be 1 for any angle #theta#. Answer linkAug 20, 2015 · sec A = 1/cos A tan A = sin A/cos A sin^2 A + cos^2 A = 1 sec x + tan x = (1+sin x)/cos x = ((1+sin x)(1-sin x))/(cos x(1-sin x)) = (1-sin^2 x)/(cos x(1-sin x)) = cos ... Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor.Precalculus. Solve for ? cos (x)=1/3. cos (x) = 1 3 cos ( x) = 1 3. Take the inverse cosine of both sides of the equation to extract x x from inside the cosine. x = arccos(1 3) x = arccos ( 1 3) Simplify the right side. Tap for more steps... x = 1.23095941 x = 1.23095941. The cosine function is positive in the first and fourth quadrants.cos^2 x + sin^2 x = 1. sin x/cos x = tan x. You want to simplify an equation down so you can use one of the trig identities to simplify your answer even more. some other identities (you will learn later) include -. cos x/sin x = cot x. 1 + tan^2 x = sec^2 x. 1 + cot^2 x = csc^2 x. hope this helped!Multiply by 1 + cosx 1 + cosx to get. 1 − cos2x x(1 + cosx) = sin2x x(1 +cosx) = sinx ⋅ sinx x ⋅ 1 1 + cosx. Taking the limit as x → 0 gives. (0)(1)(1 2) = 0. Answer link.Solve for ? cos (x)=1/2. cos (x) = 1 2 cos ( x) = 1 2. Take the inverse cosine of both sides of the equation to extract x x from inside the cosine. x = arccos(1 2) x = arccos ( 1 2) Simplify the right side. Tap for more steps... x = π 3 x = π 3. The cosine function is positive in the first and fourth quadrants.Solve for ? cos (x)=1/2. cos (x) = 1 2 cos ( x) = 1 2. Take the inverse cosine of both sides of the equation to extract x x from inside the cosine. x = arccos(1 2) x = arccos ( 1 2) Simplify the right side. Tap for more steps... x = π 3 x = π 3. The cosine function is positive in the first and fourth quadrants.First of all, note that implicitly differentiating cos(cos−1x)= x does not prove the existence of the derivative of cos−1 x. What it does show, however, ... By definition we have that for x ∈ [0,2π] for 0 ≤ x≤ π cos−1 cosx = x for π< x ≤ 2π cos−1 cosx = 2π−x and this is periodic with period T = 2π. Thus it ...1+cosx. Natural Language; Math Input; Extended Keyboard Examples Upload Random. Compute answers using Wolfram's breakthrough technology & knowledgebase, relied on by ... Jun 24, 2016 · Hero and Nghi, I think I could invoke more interest by including the. solutions for cosx − sinx = 1, and for that matter, secx ± tanx = 1, that become. cosx − sinx = 1 and cosx +sinx = 1, upon multiplication by. cos x, when x ≠ an odd multiple of π 2. For cos x - sin x = 1, the general solution is. x = 2nπ and x = (4n − 1) π 2,n = 0 ... The answer is related to the length of a side of a regular n -gon inscribed into a unit-radius circumference; because the perimeter of the n -gon is always less than 2π, the single side must always be less than 2π / n. The inequality. 1 − cos(x) ≤ x2 2 (1) is used and the proof is completed with. 2(1 − cos(x)) ≤ (2π / n)2.What is the formula of (1 - cos x) / sin x? Solution: As we know that (1 - cos x) = 2sin 2 (x/2) and sin x = 2sin (x/2).cos (x/2) (1 - cos x) = 2sin 2 (x/2) ---- (1 ... May 4, 2018 · Explanation: since cosx < 0 then x is in second/third quadrants. x = cos−1( 1 √2) = π 4 ← related acute angle. ⇒ x = π− π 4 = 3π 4 ← second quadrant. or x = π+ π 4 = 5π 4 ← third quadrant. due to the periodicity of the cosine the solutions will. repeat every 2π. solutions are. x = 3π 4 +2nπ → (n ∈ Z) First sketch 1-cos x then x. Determine where functions 1-cos x and x are positive and negative to determine where (1-cos x)/x will be positive and negative. Find any asymptotes (x=0). To help sketch determin whether the function is odd and even. If required check for concavity using the second derivative as well as max and minimumsWe will begin by multiplying 1 cosx − 1 by the conjugate of cosx − 1, which is cosx + 1: 1 cosx − 1 ⋅ cosx + 1 cosx + 1. You may wonder why we do this. It's so we can apply the difference of squares property, (a −b)(a +b) = a2 −b2, in the denominator, to simplify it a little. Back to the problem:Aug 20, 2015 · sec A = 1/cos A tan A = sin A/cos A sin^2 A + cos^2 A = 1 sec x + tan x = (1+sin x)/cos x = ((1+sin x)(1-sin x))/(cos x(1-sin x)) = (1-sin^2 x)/(cos x(1-sin x)) = cos ... What is the formula of (1 - cos x) / sin x? Solution: As we know that (1 - cos x) = 2sin 2 (x/2) and sin x = 2sin (x/2).cos (x/2) (1 - cos x) = 2sin 2 (x/2) ---- (1 ...Dividing by cos2A, you get 1+tan2A= cos2A1 that implies cos2A= 1+tan2A1 ... Show that there is a bounded linear functional ℓ: C [0,1] → R with ∥ℓ∥ ≤ 1, ℓ(1) = 0, ℓ(cos(x)) = 1. https://math.stackexchange.com/questions/1798641/show-that-there-is-a-bounded-linear-functional-ell-mathscr-c-0-1-to-mathb. Fleur Jul 5, 2017 graph{cos x + 1 [-10, 10, -5, 5]} If you graph the function, you can see that the domain includes all real numbers, and the range includes all values from 0 to 2, ...We would like to show you a description here but the site won’t allow us.From Pythagoras theorem we get: sin2x +cos2x = 1. So: sin2x = 1 − cos2x = (1 − cosx)(1 + cosx) Answer link.2cos(x)sin(x) Which we can say it's a sum. cos(x)sin(x) + sin(x)cos(x) Which is the double angle formula of the sine. cos(x)sin(x) + sin(x)cos(x) = sin(2x) But since we multiplied by 2 early on to get to that, we need to divide by two to make the equality, so. cos(x)sin(x) = sin(2x) 2. Answer link.Cos x = -1. Cách giải phương trình cos x = a (*) B. Phương trình lượng giác thường gặp. Cách giải phương trình lượng giác cơ bản đưa ra phương pháp và các ví dụ cụ thể, giúp các bạn học sinh THPT ôn tập và củng cố kiến thức về dạng toán hàm số lượng giác 12. Tài liệu ...The Cosine function ( cos (x) ) The cosine is a trigonometric function of an angle, usually defined for acute angles within a right-angled triangle as the ratio of the length of the adjacent side to the hypotenuse. It is the complement to the sine. In the illustration below, cos (α) = b/c and cos (β) = a/c.In mathematics, the trigonometric functions (also called circular functions, angle functions or goniometric functions [1] [2]) are real functions which relate an angle of a right-angled triangle to ratios of two side lengths.First sketch 1-cos x then x. Determine where functions 1-cos x and x are positive and negative to determine where (1-cos x)/x will be positive and negative. Find any asymptotes (x=0). To help sketch determin whether the function is odd and even. If required check for concavity using the second derivative as well as max and minimums(cotx)2 +1 = (cosecx)2 Odd and even properties cos( x) = cos(x) sin( x) = sin(x) tan( x) = tan(x) Double angle formulas sin(2x) = 2sinxcosx cos(2x) = (cosx)2 (sinx)2 cos(2x) = 2(cosx)2 1 cos(2x) = 1 2(sinx)2 Half angle formulas sin(1 2 x) 2 = 1 2 (1 cosx) cos(1 2 x) 2 = 1 2 (1+cosx) Sums and di erences of angles cos(A+B) = cosAcosB sinAsinB cos ... 1-cos^{2}x. en. Related Symbolab blog posts. Practice, practice, practice. Math can be an intimidating subject. Each new topic we learn has symbols and problems we ... Sep 30, 2016 · Explanation: The function cos(x) has period 2π and cos(0) = 1. Hence: cos(2nπ) = 1 for any integer n. graph {cos (x) [-10, 10, -5, 5]} Answer link. Sep 30, 2016 · Explanation: The function cos(x) has period 2π and cos(0) = 1. Hence: cos(2nπ) = 1 for any integer n. graph {cos (x) [-10, 10, -5, 5]} Answer link. VDOM DHTML tml>. What is the formula of 1+cosx? - Quora. Something went wrong.Jun 24, 2016 · This can be done by the useful technique of differentiating under the integral sign. In fact, this is exercise 10.23 in the second edition of "Mathematical Analysis" by Tom Apostol. The area, 1 / 2 × base × height, of an isosceles triangle is calculated, first when upright, and then on its side. When upright, the area = sin θ cos θ {\displaystyle \sin \theta \cos \theta } . Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor.In mathematics, the trigonometric functions (also called circular functions, angle functions or goniometric functions [1] [2]) are real functions which relate an angle of a right-angled triangle to ratios of two side lengths. Free Pre-Algebra, Algebra, Trigonometry, Calculus, Geometry, Statistics and Chemistry calculators step-by-stepFree trigonometric equation calculator - solve trigonometric equations step-by-stepHero and Nghi, I think I could invoke more interest by including the. solutions for cosx − sinx = 1, and for that matter, secx ± tanx = 1, that become. cosx − sinx = 1 and cosx +sinx = 1, upon multiplication by. cos x, when x ≠ an odd multiple of π 2. For cos x - sin x = 1, the general solution is. x = 2nπ and x = (4n − 1) π 2,n = 0 ...What is tan 30 using the unit circle? tan 30° = 1/√3. To find this answer on the unit circle, we start by finding the sin and cos values as the y-coordinate and x-coordinate, respectively: sin 30° = 1/2 and cos 30° = √3/2. Now use the formula. Recall that tan 30° = sin 30° / cos 30° = (1/2) / (√3/2) = 1/√3, as claimed.The inverse of sine is denoted as arccos or cos-1 x. For a right triangle with sides 1, 2, and √3, the cos function can be used to measure the angle. In this, the cos of angle A will be, cos(a)= adjacent/hypotenuse. Trigonometry Solve for ? cos (x)=-1 cos (x) = −1 cos ( x) = - 1 Take the inverse cosine of both sides of the equation to extract x x from inside the cosine. x = arccos(−1) x = arccos ( - 1) Simplify the right side. Tap for more steps... x = π x = π The cosine function is negative in the second and third quadrants.(cotx)2 +1 = (cosecx)2 Odd and even properties cos( x) = cos(x) sin( x) = sin(x) tan( x) = tan(x) Double angle formulas sin(2x) = 2sinxcosx cos(2x) = (cosx)2 (sinx)2 cos(2x) = 2(cosx)2 1 cos(2x) = 1 2(sinx)2 Half angle formulas sin(1 2 x) 2 = 1 2 (1 cosx) cos(1 2 x) 2 = 1 2 (1+cosx) Sums and di erences of angles cos(A+B) = cosAcosB sinAsinB cos ...Aug 14, 2015 · 1 Answer. Chandra S. Aug 14, 2015. cos x = - 1/2 = cos 2 π /3 ⇒ x = 2 π /3. Aug 14, 2023 · What is tan 30 using the unit circle? tan 30° = 1/√3. To find this answer on the unit circle, we start by finding the sin and cos values as the y-coordinate and x-coordinate, respectively: sin 30° = 1/2 and cos 30° = √3/2. Now use the formula. Recall that tan 30° = sin 30° / cos 30° = (1/2) / (√3/2) = 1/√3, as claimed. Jan 26, 2017 · Explanation: Use the identity: secx = 1 cosx. 1 secx = 1 1 cosx = 1 ⋅ cosx 1 = cosx. Answer link. Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor.First of all, note that implicitly differentiating cos(cos−1x)= x does not prove the existence of the derivative of cos−1 x. What it does show, however, ... By definition we have that for x ∈ [0,2π] for 0 ≤ x≤ π cos−1 cosx = x for π< x ≤ 2π cos−1 cosx = 2π−x and this is periodic with period T = 2π. Thus it ...So I've been trying to show that $ | \cos x - 1 | \leq | x | $ for all x values, usin... Stack Exchange Network Stack Exchange network consists of 183 Q&A communities including Stack Overflow , the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.Write each expression with a common denominator of (1−cos(x))(1+ cos(x)) ( 1 - cos ( x)) ( 1 + cos ( x)), by multiplying each by an appropriate factor of 1 1. Tap for more steps... Combine the numerators over the common denominator. Simplify the numerator.When cos x = 1, what does x equal? Trigonometry Trigonometric Identities and Equations Solving Trigonometric Equations 1 Answer George C. · Ratnaker Mehta Sep 30, 2016 x can be any integer multiple of 2π, including 0 Explanation: The function cos(x) has period 2π and cos(0) = 1 Hence: cos(2nπ) = 1 for any integer n graph {cos (x) [-10, 10, -5, 5]}Solution. Determine the formula of 1 - cos x sin x. It is known that 1 - c o s ( 2 θ) = 2 s i n 2 θ and s i n ( 2 θ) = 2 s i n θ c o s θ. So, 1 - cos x = 2 sin 2 x 2 and sin x = 2 sin x 2 cos x 2. Substitute the values into the expression 1 - cos x sin x and simplify: Hence, the formula for 1 - cos x sin x is tan x 2. What is the formula of (1 - cos x) / sin x? Solution: As we know that (1 - cos x) = 2sin 2 (x/2) and sin x = 2sin (x/2).cos (x/2) (1 - cos x) = 2sin 2 (x/2) ---- (1 ... 1. You may get numerical errors because cosh (x) grows very quickly. Write the equation as. cos(x) = 1 coshx cos ( x) = 1 cosh x, When x x is large, the solutions are going to be approximately. cos(x) = 0 cos ( x) = 0. *** cos(x) cosh(x) − 1 = 0 cos ( x) cosh ( x) − 1 = 0 is the frequency equation of an Euler-Bernoulli beam under free-free ...Graph y=cos(x-1) Step 1. Use the form to find the variables used to find the amplitude, period, phase shift, and vertical shift. Step 2. Find the amplitude . Amplitude:Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor. Oct 3, 2016 · Multiply by 1 + cosx 1 + cosx to get. 1 − cos2x x(1 + cosx) = sin2x x(1 +cosx) = sinx ⋅ sinx x ⋅ 1 1 + cosx. Taking the limit as x → 0 gives. (0)(1)(1 2) = 0. Answer link. False due to a clash of conventions. If n > 1 is a positive integer, then: cos^n x = (cos x)^n This is a convenience of notation, to avoid having to use parentheses to distinguish, for example: (cos x)^2 and cos (x^2) By convention we can write: cos^2 x and cos x^2 respectively, without ambiguity. However, in the case of -1, we have a clash of notation. If f(x) is a function, then f^(-1)(x) is ...Trigonometry. Solve for ? cos (x)=-1/2. cos (x) = − 1 2 cos ( x) = - 1 2. Take the inverse cosine of both sides of the equation to extract x x from inside the cosine. x = arccos(−1 2) x = arccos ( - 1 2) Simplify the right side. Tap for more steps... x = 2π 3 x = 2 π 3. The cosine function is negative in the second and third quadrants.Just as the distance between the origin and any point #(x,y)# on a circle must be the circle's radius, the sum of the squared values for #sin theta# and #cos theta# must be 1 for any angle #theta#. Answer linkPrecalculus. Solve for x 2cos (x)-1=0. 2cos (x) − 1 = 0 2 cos ( x) - 1 = 0. Add 1 1 to both sides of the equation. 2cos(x) = 1 2 cos ( x) = 1. Divide each term in 2cos(x) = 1 2 cos ( x) = 1 by 2 2 and simplify. Tap for more steps... cos(x) = 1 2 cos ( x) = 1 2. Take the inverse cosine of both sides of the equation to extract x x from inside ... Multiply by 1 + cosx 1 + cosx to get. 1 − cos2x x(1 + cosx) = sin2x x(1 +cosx) = sinx ⋅ sinx x ⋅ 1 1 + cosx. Taking the limit as x → 0 gives. (0)(1)(1 2) = 0. Answer link.In mathematics, the trigonometric functions (also called circular functions, angle functions or goniometric functions [1] [2]) are real functions which relate an angle of a right-angled triangle to ratios of two side lengths. May 27, 2017 · The first step is to multiply the two expressions between parentheses : (II) There is a trigonometric identity that states : Working with this expression : ⇒. (I) Using the equation (I) in (II) : ⇒. arrow right. Found 2 solutions by josgarithmetic, Boreal: Answer by josgarithmetic (38702) ( Show Source ): You can put this solution on YOUR website! Answer by Boreal (15207) ( Show Source ): You can put this solution on YOUR website! cosx/ (1+sinx) cos x (1-sinx)/ [ (1+sinx) (1-sinx)] ;; multiply by (1-sin x/1-sin x) cosx-sinxcosx/ (1-sin^2x) ;;; 1-sin^2x ...It follows that. arccos(cos x) = arccos(cos(d(x))) = d(x) (x ∈ R) , arccos ( cos x) = arccos ( cos ( d ( x))) = d ( x) ( x ∈ R) , which reveals arccos ∘ cos arccos ∘ cos to be a sawtooth function. Share. edited Aug 29, 2018 at 1:58. user46234. answered Mar 10, 2018 at 17:31. Christian Blatter.The inverse of sine is denoted as arccos or cos-1 x. For a right triangle with sides 1, 2, and √3, the cos function can be used to measure the angle. In this, the cos of angle A will be, cos(a)= adjacent/hypotenuse.Dec 9, 2014 · My origin equation is 2 x^2 (-1 + Cos[x] Cosh[x]) == 0, how could I know I should first divide the equation by x^2, before applying your code on big x approximation. The usual principal values of the arcsin(x) and arccos(x) functions graphed on the Cartesian plane. The inverse function of sine is arcsine (arcsin or asin) or inverse sine (sin −1). The inverse function of cosine is arccosine (arccos, acos, or cos −1). (The superscript of −1 in sin −1 and cos −1 denotes the inverse of a function, not ...Explanation: since cosx < 0 then x is in second/third quadrants. x = cos−1( 1 √2) = π 4 ← related acute angle. ⇒ x = π− π 4 = 3π 4 ← second quadrant. or x = π+ π 4 = 5π 4 ← third quadrant. due to the periodicity of the cosine the solutions will. repeat every 2π. solutions are. x = 3π 4 +2nπ → (n ∈ Z)Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor. We would like to show you a description here but the site won’t allow us.Trigonometry Solve for ? cos (x)=-1 cos (x) = −1 cos ( x) = - 1 Take the inverse cosine of both sides of the equation to extract x x from inside the cosine. x = arccos(−1) x = arccos ( - 1) Simplify the right side. Tap for more steps... x = π x = π The cosine function is negative in the second and third quadrants.Free Pre-Algebra, Algebra, Trigonometry, Calculus, Geometry, Statistics and Chemistry calculators step-by-stepCompute answers using Wolfram's breakthrough technology & knowledgebase, relied on by millions of students & professionals. For math, science, nutrition, history ... In looking through the ways to find the limit of (1-cos(x)) / x, we looked into a couple methods. The first method is the plug-in method, which involves simply plugging a into (1-cos(x)) / x for x.Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor.
False due to a clash of conventions. If n > 1 is a positive integer, then: cos^n x = (cos x)^n This is a convenience of notation, to avoid having to use parentheses to distinguish, for example: (cos x)^2 and cos (x^2) By convention we can write: cos^2 x and cos x^2 respectively, without ambiguity. However, in the case of -1, we have a clash of notation. If f(x) is a function, then f^(-1)(x) is .... Grandpa xnxx
Apr 12, 2016 · sin2x +cos2x = 1. where we can subtract cos2x from both sides to get what we have in blue above: sin2x = 1 − cos2x. Thus, this expression is equal to. sin2x. All we did was use the difference of squares property to our advantage, recognize that the expression we had is derived from the Pythagorean Identity, use it, and simplify. Hope this helps! Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor.Introduction to Trigonometric Identities and Equations; 7.1 Solving Trigonometric Equations with Identities; 7.2 Sum and Difference Identities; 7.3 Double-Angle, Half-Angle, and Reduction Formulas Solve for x cos (x)=1. cos (x) = 1 cos ( x) = 1. Take the inverse cosine of both sides of the equation to extract x x from inside the cosine. x = arccos(1) x = arccos ( 1) Simplify the right side. Tap for more steps... x = 0 x = 0. The cosine function is positive in the first and fourth quadrants. To find the second solution, subtract the ... Solve for x cos(x)(cos(x)-1)=0. Step 1. If any individual factor on the left side of the equation is equal to , the entire expression will be equal to . Step 2.Solve for x cos(x)(cos(x)-1)=0. Step 1. If any individual factor on the left side of the equation is equal to , the entire expression will be equal to . Step 2.Precalculus. Solve for x 2cos (x)-1=0. 2cos (x) − 1 = 0 2 cos ( x) - 1 = 0. Add 1 1 to both sides of the equation. 2cos(x) = 1 2 cos ( x) = 1. Divide each term in 2cos(x) = 1 2 cos ( x) = 1 by 2 2 and simplify. Tap for more steps... cos(x) = 1 2 cos ( x) = 1 2. Take the inverse cosine of both sides of the equation to extract x x from inside ... Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor. Solve for x cos (x)=1. cos (x) = 1 cos ( x) = 1. Take the inverse cosine of both sides of the equation to extract x x from inside the cosine. x = arccos(1) x = arccos ( 1) Simplify the right side. Tap for more steps... x = 0 x = 0. The cosine function is positive in the first and fourth quadrants. To find the second solution, subtract the ... Write each expression with a common denominator of (1+cos(x))(1− cos(x)) ( 1 + cos ( x)) ( 1 - cos ( x)), by multiplying each by an appropriate factor of 1 1. Tap for more steps... Combine the numerators over the common denominator. Simplify the numerator.The Cosine function ( cos (x) ) The cosine is a trigonometric function of an angle, usually defined for acute angles within a right-angled triangle as the ratio of the length of the adjacent side to the hypotenuse. It is the complement to the sine. In the illustration below, cos (α) = b/c and cos (β) = a/c.Precalculus. Solve for ? cos (x)=1/3. cos (x) = 1 3 cos ( x) = 1 3. Take the inverse cosine of both sides of the equation to extract x x from inside the cosine. x = arccos(1 3) x = arccos ( 1 3) Simplify the right side. Tap for more steps... x = 1.23095941 x = 1.23095941. The cosine function is positive in the first and fourth quadrants..