1. verified. Simplify the first trigonometric expression by writing the simplified form in terms of the second expression. 1. 1/1-cos (x) - cos (x)/1+cos (x) ; csc (x) 2. 1/sin (x) cos (x) - cot (x) ; cot (x) 3. cos (x)/1+sin (x) + tan (x) ; cos (x) 4. tan (x) +cot (x)/sec (x) ; sin (x) verified. Prove this identity is true using trigonometric ...cos2x + cosx − 1 = 0 we obtain. cosx = 1 2( − 1 ± √5). and. sinx = √ 1 2( − 1 + √5) Putting this results into the big equation. sin12x + ⋯ + sin6x we obtain the answer. Example. (√ 1 2( − 1 + √5))16 = 1 2 (47 −21√5) so the answer is.Show algebraically cos2x = cos^2x - sin^2x using the sum and difference identities. Verify the Identity: cos^2 t/sin t = csc t - sin t. Verify the identity: 1 - (cos^2 x)/ (1 - sin x) = -sin x. Verify that the equation is an identity. cos 2x + 1 = 2 cos^2 x.subtract 1 from both sides. tan2x+1 −1 = sec2x −1. ⇒ sec2x −1 = tan2x. Answer link.1 + cos. 2x = 2cos 2 x. 1 – cos2x = 2sin² x. The cos 2 x formula is essentially used to resolve the integration problems. It will be used as. cos 2 x = (cos2x + 1)/2. If you want to solve the integral of (1 – cos 2 x) and (1 + cos 2 x). Both mathematical terms will be calculated with the help of trigonometric identities. We have cos 2 x= 1 ...Ratnaker Mehta. Sep 2, 2016. ∫ 1 (cosx)2 dx = ∫sec2xdx = tanx + C. Answer link.In this video I will prove cos^2(x)=(1+cos2x)/2. Course Index. What Is The Unit Circle? The Unit Circle and The Angle (Part 1 of 2) The Unit Circle and The Angle ...What is the value of 1+cos^2 (x)? - Quora. Something went wrong. Wait a moment and try again. Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor. Explanation for correct option: Find the value of lim x → 2 1 - cos 2 x - 2 x - 2. Consider the given Equation as. I = lim x → 2 1 - cos 2 x - 2 x - 2. We know that. cos 2 θ = 1 - 2 sin 2 θ. Then, on substituting we have, I = lim x → 2 1 - 1 - 2 sin 2 x - 2 x - 2 ⇒ I = lim x → 2 2 sin 2 x - 2 x - 2 ⇒ I = lim x → 2 2 sin x - 2 x ...Jan 23, 2017 · 🏼 https://integralsforyou.com - Integral of 1/(1+cos^2(x)) - How to integrate it step by step using the substitution method!🙈 𝐒𝐚𝐦𝐞 𝐢𝐧𝐭𝐞𝐠𝐫𝐚𝐥, ?... cos(2x) = cos 2 (x) − sin 2 (x) = 1 − 2 sin 2 (x) = 2 cos 2 (x) − 1 Half-Angle Identities The above identities can be re-stated by squaring each side and doubling all of the angle measures.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 ...You don't have to memorize all formulas but it helps to do so. If you remember, 1 = cos^2 x + sin^2 x. So we have, cos^2 x = 1 - sin^2 x and sin^2 x = 1 - cos^2 x. If we replace cos^2 x in the first double angle formula cos2x = cos^2 x - sin^2 x with 1 - sin^2 x we get: cos2x = 1 - 2 sin^2 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. Free trigonometric equation calculator - solve trigonometric equations step-by-step Free integral calculator - solve indefinite, definite and multiple integrals with all the steps. Type in any integral to get the solution, steps and graphWe would like to show you a description here but the site won’t allow us.Free trigonometric equation calculator - solve trigonometric equations step-by-stepIt is indeed true that sin2(x)= 1 −cos2(x) and that sin2(x)= 21−cos(2x). How do you use the half-angle identities to find all solutions on the interval [0,2pi) for the equation sin2x = cos2(2x) ? 3π,π and 3.5π Explanation: Use cos2a = 2cos2a−1 . The given equation is sin2x = 1−cos2x = 1−(2cos2(2x)−1)2 = cos2(2x) ...If any individual factor on the left side of the equation is equal to 0 0, the entire expression will be equal to 0 0. 2cos(x)− 1 = 0 2 cos ( x) - 1 = 0. cos(x)+1 = 0 cos ( x) + 1 = 0. Set 2cos(x)−1 2 cos ( x) - 1 equal to 0 0 and solve for x x. Tap for more steps... x = π 3 +2πn, 5π 3 +2πn x = π 3 + 2 π n, 5 π 3 + 2 π n, for any ...Compute answers using Wolfram's breakthrough technology & knowledgebase, relied on by millions of students & professionals. For math, science, nutrition, history ...Explanation: (1) Use the trigonometric formula, cos (a + b) = cos a cos b – sin a sin b and substitute a = b = x. Now write cos 2 x + sin 2 x for 1 on the right side of the equation, (2) Multiply the equation cos2x = cos 2 x - sin 2 x by negative 1 and add 1 on both sides.Free integral calculator - solve indefinite, definite and multiple integrals with all the steps. Type in any integral to get the solution, steps and graphx^{2}-x-6=0-x+3\gt 2x+1; line\:(1,\:2),\:(3,\:1) f(x)=x^3; prove\:\tan^2(x)-\sin^2(x)=\tan^2(x)\sin^2(x) \frac{d}{dx}(\frac{3x+9}{2-x}) (\sin^2(\theta))' \sin(120) \lim _{x\to 0}(x\ln (x)) \int e^x\cos (x)dx \int_{0}^{\pi}\sin(x)dx \sum_{n=0}^{\infty}\frac{3}{2^n} Show More Hint: cos(2x) = cos(x+x)= cosxcosx−sinxsinx= cos2x−sin2x= cos2x−(1−cos2x)= 2cos2x−1 So, cos2x= 21+cos(2x) which can be substituted. For which a ∈ R are sin2(ax),cos2(x) and 1 linear independent. You have sin2(x)= (1−cos(2x))/2 and cos2(ax) =(1+cos(2ax)/2. Hence the span of the three functions is the same as the span of 1, cos(2ax ...🏼 https://integralsforyou.com - Integral of 1/(1+cos^2(x)) - How to integrate it step by step using the substitution method!🙈 𝐒𝐚𝐦𝐞 𝐢𝐧𝐭𝐞𝐠𝐫𝐚𝐥, ?...We would like to show you a description here but the site won’t allow us.Let us equate, X and Y, i.e. X = Y. So, the above formula for cos 2X, becomes. cos 2X = cos(X + X) = cos X cos X– sin X sin X. cos 2X = cos2 X–sin2 X. Hence, the first cos 2X formula follows, as. cos 2X = cos2 X–sin2 X. And for this reason, we know this formula as double the angle formula, because we are doubling the angle. How do you differentiate #1+cos^2(x)#? Calculus Differentiating Trigonometric Functions Derivative Rules for y=cos(x) and y=tan(x) 1 Answer Jim G.sin^2(theta) + cos^2(theta) = 1 (Pythagorean theorem) So 1-cos^2(theta) = sin^2(theta)Precalculus. Solve for ? cos (2x)=1. cos (2x) = 1 cos ( 2 x) = 1. Take the inverse cosine of both sides of the equation to extract x x from inside the cosine. 2x = arccos(1) 2 x = arccos ( 1) Simplify the right side. Tap for more steps... 2x = 0 2 x = 0. Divide each term in 2x = 0 2 x = 0 by 2 2 and simplify.Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor.Trigonometry is a branch of mathematics concerned with relationships between angles and ratios of lengths. The field emerged in the Hellenistic world during the 3rd century BC from applications of geometry to astronomical studies.Use the identity: cos (a + b) = cos a.cos b - sin a.sin b cos 2x = cos (x + x) = cos x.cos x - sin x. sin x = cos^2 x - sin^2 x = = cos^2 x - (1 - cos^2 x) = 2cos ^2 ...Show algebraically cos2x = cos^2x - sin^2x using the sum and difference identities. Verify the Identity: cos^2 t/sin t = csc t - sin t. Verify the identity: 1 - (cos^2 x)/ (1 - sin x) = -sin x. Verify that the equation is an identity. cos 2x + 1 = 2 cos^2 x. Evaluate the integral. ∫ ( cos 2 x - 1) ( cos 2 x + 1) d x. = – ∫ ( 2 sin 2 x) ( 2 cos 2 x) d x = – ∫ tan 2 x d x = ∫ ( 1 – s e c 2 x) d x = x – tan x + C.simplify\:\tan^4(x)+2\tan^2(x)+1; simplify\:\tan^2(x)\cos^2(x)+\cot^2(x)\sin^2(x) Show More; Description. Simplify trigonometric expressions to their simplest form ...Free trigonometric equation calculator - solve trigonometric equations step-by-stepFree trigonometric equation calculator - solve trigonometric equations step-by-stepIf any individual factor on the left side of the equation is equal to 0 0, the entire expression will be equal to 0 0. 2cos(x)− 1 = 0 2 cos ( x) - 1 = 0. cos(x)+1 = 0 cos ( x) + 1 = 0. Set 2cos(x)−1 2 cos ( x) - 1 equal to 0 0 and solve for x x. Tap for more steps... x = π 3 +2πn, 5π 3 +2πn x = π 3 + 2 π n, 5 π 3 + 2 π n, for any ...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.Hint: cos(2x) = cos(x+x)= cosxcosx−sinxsinx= cos2x−sin2x= cos2x−(1−cos2x)= 2cos2x−1 So, cos2x= 21+cos(2x) which can be substituted. For which a ∈ R are sin2(ax),cos2(x) and 1 linear independent. You have sin2(x)= (1−cos(2x))/2 and cos2(ax) =(1+cos(2ax)/2. Hence the span of the three functions is the same as the span of 1, cos(2ax ...今回は\(\displaystyle\int \displaystyle \frac{1}{\cos^2 x} dx\)を積分していきます。置換積分法を使ったテクニックと微分を使って、下記の積分を実施します。Jul 21, 2023 · Step by step video solution for int(1+ cos^2(x))/(1+cos(2x))dx by Maths experts to help you in doubts & scoring excellent marks in Class 12 exams. Ab Padhai karo bina ads ke Khareedo DN Pro and dekho sari videos bina kisi ad ki rukaavat ke! Jun 25, 2018 · How do you differentiate #1+cos^2(x)#? Calculus Differentiating Trigonometric Functions Derivative Rules for y=cos(x) and y=tan(x) 1 Answer Jim G. Answer: Step-by-step explanation: Verify the Identity Cos x + cos x cot^2 x = cot x csc x 4 steps Answer choices: Cos x sec^2 x Cos x (1 + cot x) Cos x / sin x • 1 / sin x Cos x • 1 / sin^2 x Cos x (1 + cot^2 x) Cos x csc^2 xWe would like to show you a description here but the site won’t allow us. General solution for squared trigonometry questions: cos2 x = 1. https://math.stackexchange.com/q/764154. Use the identity cos2(x)= 21+cos(2x). You should then be able to solve this for x by way of the inverse. Trigonometric equation: cos3x + cosx − cos2x = 0.From Pythagoras theorem we get: sin2x +cos2x = 1. So: sin2x = 1 − cos2x = (1 − cosx)(1 + cosx) Answer link.Precalculus. Solve for ? cos (x)^2-1=0. cos2 (x) − 1 = 0 cos 2 ( x) - 1 = 0. Add 1 1 to both sides of the equation. cos2(x) = 1 cos 2 ( x) = 1. Take the specified root of both sides of the equation to eliminate the exponent on the left side. cos(x) = ±√1 cos ( x) = ± 1. Any root of 1 1 is 1 1. cos(x) = ±1 cos ( x) = ± 1.It is indeed true that sin2(x)= 1 −cos2(x) and that sin2(x)= 21−cos(2x). How do you use the half-angle identities to find all solutions on the interval [0,2pi) for the equation sin2x = cos2(2x) ? 3π,π and 3.5π Explanation: Use cos2a = 2cos2a−1 . The given equation is sin2x = 1−cos2x = 1−(2cos2(2x)−1)2 = cos2(2x) ...Trigonometry. Solve for x cos (2x)=-1. cos (2x) = −1 cos ( 2 x) = - 1. Take the inverse cosine of both sides of the equation to extract x x from inside the cosine. 2x = arccos(−1) 2 x = arccos ( - 1) Simplify the right side. Tap for more steps... 2x = π 2 x = π. Divide each term in 2x = π 2 x = π by 2 2 and simplify. Dec 2, 2018 · In this video, we are going to derive value of 1 - cosine of 2x.The identity cos(2x) has been explained in the following videohttps://youtu.be/NTgX1EY6Poo#co... 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. Trigonometry. Simplify square root of 1-cos (x)^2. √1 − cos2 (x) 1 - cos 2 ( x) Apply pythagorean identity. √sin2(x) sin 2 ( x) Pull terms out from under the radical, assuming positive real numbers. Using #color(blue)" Double angle formula "# #• cos2x = cos^2 x - sin^2 x# and the identity # cos^2x = 1 - sin^2x #. #rArrcos2x = cos^2x - sin^2x = (1-sin^2x) - sin^2x # ...Step by step video solution for int(1+ cos^2(x))/(1+cos(2x))dx by Maths experts to help you in doubts & scoring excellent marks in Class 12 exams. Ab Padhai karo bina ads ke Khareedo DN Pro and dekho sari videos bina kisi ad ki rukaavat ke!Evaluate the integral. ∫ ( cos 2 x - 1) ( cos 2 x + 1) d x. = – ∫ ( 2 sin 2 x) ( 2 cos 2 x) d x = – ∫ tan 2 x d x = ∫ ( 1 – s e c 2 x) d x = x – tan x + C. Hint: cos(2x) = cos(x+x)= cosxcosx−sinxsinx= cos2x−sin2x= cos2x−(1−cos2x)= 2cos2x−1 So, cos2x= 21+cos(2x) which can be substituted. For which a ∈ R are sin2(ax),cos2(x) and 1 linear independent. You have sin2(x)= (1−cos(2x))/2 and cos2(ax) =(1+cos(2ax)/2. Hence the span of the three functions is the same as the span of 1, cos(2ax ...幂简约公式. 从解余弦二倍角公式的第二和第三版本得到。. 正弦. 餘弦. 其他. sin 2 θ = 1 − cos 2 θ 2 \sin ^ {2}\theta = {\frac {1-\cos 2\theta } {2}} cos 2 θ = 1 + cos 2 θ 2 \cos ^ {2}\theta = {\frac {1+\cos 2\theta } {2}} sin 2 θ cos 2 θ = 1 − cos 4 θ 8 \sin ^ {2}\theta \cos ^ {2 ...1. I'm being asked to find the arc length of y = sin(x) y = sin ( x) for [0, π 2] [ 0, π 2] using M8 M 8. I've determined that y′2 =cos2 x y ′ 2 = cos 2 x. So, using the formula for arc length, I get 1 +cos2 x− −−−−−−−√ 1 + cos 2 x as my function. Now, they want me to evaluate this using M8 M 8, so I end up with 8 8 ...Trigonometry. Simplify square root of 1-cos (x)^2. √1 − cos2 (x) 1 - cos 2 ( x) Apply pythagorean identity. √sin2(x) sin 2 ( x) Pull terms out from under the radical, assuming positive real numbers. Explanation: 1 cos2x − 1 = 1 − cos2x cos2x = sin2x cos2x = tan2x. Answer link.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. The angle in the one minus cos double angle trigonometric identity can be denoted by any symbol. Hence, it also is popularly written in two distinct forms. ( 1). 1 − cos ( 2 x) = 2 sin 2 x. ( 2). 1 − cos ( 2 A) = 2 sin 2 A. In this way, the one minus cosine of double angle formula can be expressed in terms of any symbol.sin^2x. Rewrite sec^2x as 1/cos^2x by the identity secx = 1/cosx. =cos^2x(1/cos^2x- 1) = 1 - cos^2x Use the identity sin^2x + cos^2x = 1 solved for sin^2x to get: = sin^2x Hopefully this helps!cos(2x) = cos 2 (x) − sin 2 (x) = 1 − 2 sin 2 (x) = 2 cos 2 (x) − 1 Half-Angle Identities The above identities can be re-stated by squaring each side and doubling all of the angle measures.Q. Integrate w.r.to x. tan−1( √1−cos2x 1+cos2x) Q. Integrate ∫ tan−1(√ 1−cos2x 1+cos2x)dx. Q. The minimum integral value of x for which 2x2+2x+n>9+sin−1(sin(−1))+cos−1(cos(−1)) ∀x∈R, is. Q. Integrate the following: 1 √1+cos2x. Q. Integrate : ∫ 1 1−cos2xdx. View More.Here are a few examples I have prepared: a) Simplify: tanx cscx ×secx. Apply the quotient identity tanθ = sinθ cosθ and the reciprocal identities cscθ = 1 sinθ and secθ = 1 cosθ. = sinx cosx 1 sinx × 1 cosx. = sinx cosx × sinx 1 × 1 cosx. = sin2x cos2x. Reapplying the quotient identity, in reverse form: = tan2x. b) Simplify: cscβ ... Explanation: Manipulating the left side using Double angle formulae. ∙ sin2x = 2sinxcosx. ∙ cos2x = cos2x − sin2x. and using sin2x +cos2x = 1 we can also obtain. cos2x = (1 − sin2x) − sin2x = 1 −2sin2x. and cos2x = cos2x −(1 − cos2x) = 2cos2x − 1. ⇒ sin2x 1 +cos2x = 2sinxcosx 1 + 2cos2x − 1 = 2sinxcosx 2cos2x. = 2 sinxcosx ...Compute answers using Wolfram's breakthrough technology & knowledgebase, relied on by millions of students & professionals. For math, science, nutrition, history ...🏼 https://integralsforyou.com - Integral of 1/(1+cos^2(x)) - How to integrate it step by step using the substitution method!🙈 𝐒𝐚𝐦𝐞 𝐢𝐧𝐭𝐞𝐠𝐫𝐚𝐥, ?...Mar 20, 2016 · Explanation: Manipulating the left side using Double angle formulae. ∙ sin2x = 2sinxcosx. ∙ cos2x = cos2x − sin2x. and using sin2x +cos2x = 1 we can also obtain. cos2x = (1 − sin2x) − sin2x = 1 −2sin2x. and cos2x = cos2x −(1 − cos2x) = 2cos2x − 1. ⇒ sin2x 1 +cos2x = 2sinxcosx 1 + 2cos2x − 1 = 2sinxcosx 2cos2x. = 2 sinxcosx ... 1. To provide a correction to your own work I would remove the lim at first because I want to simplifies to the maximum the expression and at the last the computation, as follows: 1 − cos x x 2 = 2 sin 2 ( x 2) x 2 = 2 x 2 ⋅ sin 2 ( x 2) ( x 2) 2 ⋅ ( x 2) 2 = sin 2 ( x 2) ( x 2) 2 ⋅ 1 2. therefore. lim 1 − cos x x 2 = lim sin 2 ( x 2 ...The angle in the one plus cos double angle trigonometric identity can be represented by any symbol but it is popularly written in two different forms. ( 1). 1 + cos ( 2 x) = 2 cos 2 x. ( 2). 1 + cos ( 2 A) = 2 cos 2 A. Thus, the one plus cosine of double angle rule can be written in terms of any symbol.Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor.Let us equate, X and Y, i.e. X = Y. So, the above formula for cos 2X, becomes. cos 2X = cos(X + X) = cos X cos X– sin X sin X. cos 2X = cos2 X–sin2 X. Hence, the first cos 2X formula follows, as. cos 2X = cos2 X–sin2 X. And for this reason, we know this formula as double the angle formula, because we are doubling the angle. Compute answers using Wolfram's breakthrough technology & knowledgebase, relied on by millions of students & professionals. For math, science, nutrition, history ... Ratnaker Mehta. Sep 2, 2016. ∫ 1 (cosx)2 dx = ∫sec2xdx = tanx + C. Answer link.
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1 Answer. George C. Nov 15, 2015. Use cos2x +sin2x = 1 to find: 1 − cos2x sinx = sinx.Jun 25, 2018 · How do you differentiate #1+cos^2(x)#? Calculus Differentiating Trigonometric Functions Derivative Rules for y=cos(x) and y=tan(x) 1 Answer Jim G. See full list on purplemath.com Free Pre-Algebra, Algebra, Trigonometry, Calculus, Geometry, Statistics and Chemistry calculators step-by-stepFree Pre-Algebra, Algebra, Trigonometry, Calculus, Geometry, Statistics and Chemistry calculators step-by-stepIn trigonometry formulas, we will learn all the basic formulas based on trigonometry ratios (sin,cos, tan) and identities as per Class 10, 11 and 12 syllabi. Also, find the downloadable PDF of trigonometric formulas at BYJU'S. You don't have to memorize all formulas but it helps to do so. If you remember, 1 = cos^2 x + sin^2 x. So we have, cos^2 x = 1 - sin^2 x and sin^2 x = 1 - cos^2 x. If we replace cos^2 x in the first double angle formula cos2x = cos^2 x - sin^2 x with 1 - sin^2 x we get: cos2x = 1 - 2 sin^2 x. Feb 17, 2016 · x_1=pi/4 and x_2=(3pi)/4 First, take the half over to the other side to get: cos^2(x) =1/2 then square root: cos(x)=1/sqrt(2). We now need to find the inverse of this. If we look at the graph of cos(x) over the given region we see: graph{cos(x) [-0.1,6.15,-1.2,1.2]} We should expect two answers. 1/sqrt(2) is the exact value for cos(pi/4) So we know at least x_1 = cos^-1(1/sqrt2) ->x_1=pi/4 ... Evaluate the integral. integral cos^2 x sin^2x dx; How to integrate 1/tan(x)^2; Use the identity \cos^2 x + \sin^2 x = 1 to integrate \int \cos^3 x \sin ^2 x dx. Calculate: integral_0^pi/2 7 sin^2 x cos^2 x dx =. Find the antiderivative: integral x/x^2 - 25 dx = Evaluate the integral \int cos^2x sin x dx.Explanation: (1) Use the trigonometric formula, cos (a + b) = cos a cos b – sin a sin b and substitute a = b = x. Now write cos 2 x + sin 2 x for 1 on the right side of the equation, (2) Multiply the equation cos2x = cos 2 x - sin 2 x by negative 1 and add 1 on both sides.Free math problem solver answers your algebra, geometry, trigonometry, calculus, and statistics homework questions with step-by-step explanations, just like a math tutor.Trigonometry Simplify 1-cos (x)^2 1 − cos2 (x) 1 - cos 2 ( x) Apply pythagorean identity. sin2(x) sin 2 ( x) 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. .