Please see below. sec^2x(1-cos^2x) = sec^2x-sec^2x xx cos^2x = sec^2x-1/cos^2x xx cos^2x = 1+tan^2x-1/cancel(cos^2x) xx cancel(cos^2x) = 1+tan^2x-1 = tan^2x
You are using an out of date browser. It may not display this or other websites should upgrade or use an alternative browser. Forums Homework Help Precalculus Mathematics Homework Help What does (cos(2x))^2 equal? Thread starter justine411 Start date Apr 11, 2007 Apr 11, 2007 #1 Homework Statement (cos2x)^2Homework EquationsThe Attempt at a Solution I'm not sure if it is cos^2(2x) or cos^2(4x) or what. Should I use an identity to simplify it to make it easier to solve? Please help! :) Answers and Replies Apr 11, 2007 #2 What is there to solve??? (cos2x)^2 is just an expression. Apr 11, 2007 #3 In what sense is (cos(2x))2 a "problem"? What do you want to do with it? I will say that (cos(2x))2 means: First calculate 2x, then find cosine of that and finally square that result. Notice that it is still 2x, not 4x. The fact that 2 is outside the parentheses means that it only applies to the final result. Apr 12, 2007 #4 In what sense is (cos(2x))2 a "problem"? What do you want to do with it? I will say that (cos(2x))2 means: First calculate 2x, then find cosine of that and finally square that result. Notice that it is still 2x, not 4x. The fact that 2 is outside the parentheses means that it only applies to the final result. Doesn't (cos(2x))2 = cos2(2x)2 = cos2(4x2) ? Apr 12, 2007 #5 Doesn't (cos(2x))2 = cos2(2x)2 = cos2(4x2) ? No. 'Cos' is a particular operation and 2x is the argument. The exponent of 2 operates on cos, not on the argument. cos2y = cos y * cos y. There are also particular trigonometric identites with which one should be familiar, cos (x+y) and sin (x+y). Apr 12, 2007 #6 You still haven't told us what the problem was! Was it to write (cos(2x))^2 in terms of sin(x) and cos(x)? I would simply be inclined to write (cos(2x))^2 as cos^2(2x). Suggested for: What does (cos(2x))^2 equal? Last Post Jan 25, 2012 Last Post Nov 29, 2007 Last Post Jun 21, 2015 Last Post Apr 29, 2018 Last Post Sep 23, 2007 Last Post Apr 9, 2015 Last Post Feb 3, 2011 Last Post Sep 17, 2011 Last Post Apr 11, 2014 Last Post Jan 20, 2006 Forums Homework Help Precalculus Mathematics Homework Help Join Physics Forums Today! The friendliest, high quality science and math community on the planet! Register for no ads!
Trigonometry Solve for x cos (2x)=1/2 cos (2x) = 1 2 cos ( 2 x) = 1 2 Take the inverse cosine of both sides of the equation to extract x x from inside the cosine. 2x = arccos(1 2) 2 x = arccos ( 1 2) Simplify the right side. Tap for more steps 2x = π 3 2 x = π 3 Divide each term in 2x = π 3 2 x = π 3 by 2 2 and simplify. Tap for more steps Chapter 5 Class 12 Continuity and Differentiability Serial order wise Ex Check sibling questions Ex Ex 1 Ex 2 Ex 3 Ex 4 Important Ex 5 Ex 6 Ex 7 Important Ex 8 Ex 9 Important Ex 10 Important Ex 11 Important Ex 12 Important Ex 13 Important You are here Ex 14 Ex 15 Important Ex 13 - Chapter 5 Class 12 Continuity and Differentiability (Term 1) Last updated at March 11, 2021 by Introducing your new favourite teacher - Teachoo Black, at only ₹83 per month Chapter 5 Class 12 Continuity and Differentiability Serial order wise Ex Ex 1 Ex 2 Ex 3 Ex 4 Important Ex 5 Ex 6 Ex 7 Important Ex 8 Ex 9 Important Ex 10 Important Ex 11 Important Ex 12 Important Ex 13 Important You are here Ex 14 Ex 15 Important Transcript Ex 13 Find 𝑑𝑦/𝑑𝑥 in, y = cos–1 (2𝑥/( 1+ 𝑥2 )) , −1 < x < 1 𝑦 = cos–1 (2𝑥/( 1+ 𝑥2 )) Let 𝑥 = tan⁡𝜃 𝑦 = cos–1 ((2 tan⁡𝜃)/( 1 + 𝑡𝑎𝑛2𝜃 )) 𝑦 = cos–1 (sin 2θ) 𝑦 ="cos–1" (〖cos 〗⁡(𝜋/2 −2𝜃) ) 𝑦 = 𝜋/2 − 2𝜃 Putting value of θ = tan−1 x 𝑦 = 𝜋/2 − 2 〖𝑡𝑎𝑛〗^(−1) 𝑥 Since x = tan θ ∴ 〖𝑡𝑎𝑛〗^(−1) x = θ Differentiating both sides (𝑑(𝑦))/𝑑𝑥 = (𝑑 (" " 𝜋/2 " − " 〖2𝑡𝑎𝑛〗^(−1) 𝑥" " ))/𝑑𝑥 𝑑𝑦/𝑑𝑥 = 0 − 2 (𝑑〖 (𝑡𝑎𝑛〗^(−1) 𝑥))/𝑑𝑥 𝑑𝑦/𝑑𝑥 = − 2 (𝑑〖 (𝑡𝑎𝑛〗^(−1) 𝑥))/𝑑𝑥 𝑑𝑦/𝑑𝑥 = − 2 (1/(1 + 𝑥^2 )) 𝒅𝒚/𝒅𝒙 = (−𝟐)/(𝟏 + 𝒙^𝟐 ) ((〖𝑡𝑎𝑛〗^(−1) 𝑥") ‘ = " 1/(1 + 𝑥^2 )) Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths and Science at Teachoo. Proof of $\sin^2 x+\cos^2 x=1$ using Euler's Formula. Ask Question Asked 10 years, 9 months ago. Modified 6 years, 6 months ago. Viewed 20k times One plus Cosine double angle identity Math Doubts Trigonometry Formulas Double angle Cosine $1+\cos{(2\theta)} \,=\, 2\cos^2{\theta}$ A trigonometric identity that expresses the addition of one and cosine of double angle as the two times square of cosine of angle is called the one plus cosine double angle identity. Introduction If the theta ($\theta$) is used to represent an angle of a right triangle, the sum of one and cosine of double angle is mathematically written as follows. $1+\cos{2\theta}$ The sum of one and cosine of double angle is mathematically equal to the two times the cosine squared of angle. It can be expressed in mathematical form as follows. $\implies$ $1+\cos{(2\theta)}$ $\,=\,$ $2\cos^2{\theta}$ Usage The one plus cosine of double angle identity is mostly used as a formula in two different cases in the trigonometry. Simplified form It is used to simplify the one plus cos of double angle as two times the square of cosine of angle. $\implies$ $1+\cos{(2\theta)} \,=\, 2\cos^2{\theta}$ Expansion It is used to expand the two times cos squared of angle as the one plus cosine of double angle. $\implies$ $2\cos^2{\theta} \,=\, 1+\cos{(2\theta)}$ Other forms 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 $(1). \,\,\,$ $1+\cos{(2x)} \,=\, 2\cos^2{x}$ $(2). \,\,\,$ $1+\cos{(2A)} \,=\, 2\cos^2{A}$ Thus, the one plus cosine of double angle rule can be written in terms of any symbol. Proof Learn how to derive the one plus cosine of double angle trigonometric identity in trigonometry.
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Therefore: cos2x − sin2x = 1 − 2sin2x. Answer link. Below RTP: cos^2x-sin^2x=1-2sin^2x LHS: cos^2x-sin^2x Recall: cos^2x+sin^2x=1 so cos^2x=1-sin^2x = (1-sin^2x)-sin^2x =1-sin^2x-sin^2x = 1-2sin^2x = RHS Therefore: cos^2x-sin^2x=1-2sin^2x. \bold{\mathrm{Basic}} \bold{\alpha\beta\gamma} \bold{\mathrm{AB\Gamma}} \bold{\sin\cos} \bold{\ge\div\rightarrow} \bold{\overline{x}\space\mathbb{C}\forall} \bold{\sum\space\int\space\product} \bold{\begin{pmatrix}\square&\square\\\square&\square\end{pmatrix}} \bold{H_{2}O} \square^{2} x^{\square} \sqrt{\square} \nthroot[\msquare]{\square} \frac{\msquare}{\msquare} \log_{\msquare} \pi \theta \infty \int \frac{d}{dx} \ge \le \cdot \div x^{\circ} (\square) |\square| (f\:\circ\:g) f(x) \ln e^{\square} \left(\square\right)^{'} \frac{\partial}{\partial x} \int_{\msquare}^{\msquare} \lim \sum \sin \cos \tan \cot \csc \sec \alpha \beta \gamma \delta \zeta \eta \theta \iota \kappa \lambda \mu \nu \xi \pi \rho \sigma \tau \upsilon \phi \chi \psi \omega A B \Gamma \Delta E Z H \Theta K \Lambda M N \Xi \Pi P \Sigma T \Upsilon \Phi X \Psi \Omega \sin \cos \tan \cot \sec \csc \sinh \cosh \tanh \coth \sech \arcsin \arccos \arctan \arccot \arcsec \arccsc \arcsinh \arccosh \arctanh \arccoth \arcsech \begin{cases}\square\\\square\end{cases} \begin{cases}\square\\\square\\\square\end{cases} = \ne \div \cdot \times \le \ge (\square) [\square] ▭\:\longdivision{▭} \times \twostack{▭}{▭} + \twostack{▭}{▭} - \twostack{▭}{▭} \square! x^{\circ} \rightarrow \lfloor\square\rfloor \lceil\square\rceil \overline{\square} \vec{\square} \in \forall \notin \exist \mathbb{R} \mathbb{C} \mathbb{N} \mathbb{Z} \emptyset \vee \wedge \neg \oplus \cap \cup \square^{c} \subset \subsete \superset \supersete \int \int\int \int\int\int \int_{\square}^{\square} \int_{\square}^{\square}\int_{\square}^{\square} \int_{\square}^{\square}\int_{\square}^{\square}\int_{\square}^{\square} \sum \prod \lim \lim _{x\to \infty } \lim _{x\to 0+} \lim _{x\to 0-} \frac{d}{dx} \frac{d^2}{dx^2} \left(\square\right)^{'} \left(\square\right)^{''} \frac{\partial}{\partial x} (2\times2) (2\times3) (3\times3) (3\times2) (4\times2) (4\times3) (4\times4) (3\times4) (2\times4) (5\times5) (1\times2) (1\times3) (1\times4) (1\times5) (1\times6) (2\times1) (3\times1) (4\times1) (5\times1) (6\times1) (7\times1) \mathrm{Radians} \mathrm{Degrees} \square! ( ) % \mathrm{clear} \arcsin \sin \sqrt{\square} 7 8 9 \div \arccos \cos \ln 4 5 6 \times \arctan \tan \log 1 2 3 - \pi e x^{\square} 0 . \bold{=} + Related » Graph » Number Line » Similar » Examples » Our online expert tutors can answer this problem Get step-by-step solutions from expert tutors as fast as 15-30 minutes. Your first 5 questions are on us! You are being redirected to Course Hero I want to submit the same problem to Course Hero Correct Answer :) Let's Try Again :( Try to further simplify Number Line Graph Hide Plot » Sorry, your browser does not support this application Examples x^{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} step-by-step sin^{2}x-cos^{2}x en
2sinxcosx = sin2x, while 1 − 2sin2x = sin2x + cos2x − 2sin2x = cos2x − sin2x = cos2x. Thus tan2x = sin2x cos2x. Share. Cite. Follow. answered Apr 30, 2018 at 12:11. Lorenzo B. 2,252 2 11 25. You don't have to prove 1 − 2sin2x = cos2x: it is one of the basic duplication formulæ.
Profile Edit Profile Messages Favorites My Updates Logout User qa_get_logged_in_handle sort Home Class 10th What is the domain of the function cos^-1 (2x –... User qa_get_logged_in_handle sort What is the domain of the function cos^-1 (2x – 3) Home Class 10th What is the domain of the function cos^-1 (2x –... by Chief of LearnyVerse (321k points) asked in Class 10th Mar 23 30 views What is the domain of the function cos^-1 (2x – 3)(a) [-1, 1](b) (1, 2)(c) (-1, 1)(d) [1, 2] 1 Answer Related questions
Precalculus. Solve for ? cos (x)^2=1/4. cos2 (x) = 1 4 cos 2 ( x) = 1 4. Take the specified root of both sides of the equation to eliminate the exponent on the left side. cos(x) = ±√1 4 cos ( x) = ± 1 4. Simplify ±√1 4 ± 1 4. Tap for more steps cos(x) = ±1 2 cos ( x) = ± 1 2.

Let x = tan θ. Then, θ = tan−1 x. `:. sin^(-1) (2x)/(1+x^2 ) = sin^(-1) ((2tan theta)/(1 + tan^2 theta)) = sin^(-1) (sin 2 theta) = 2theta = 2 tan^(-1) x` Let y = tan Φ. Then, Φ = tan−1 y. `:. cos^(-1) (1 - y^2)/(1+ y^2) = cos^(-1) ((1 - tan^2 phi)/(1+tan^2 phi)) = cos^(-1)(cos 2phi) = 2phi = 2 tan^(-1) y` `:. tan 1/2 [sin^(-1) "2x"/(1+x^2) + cos^(-1) (1-y^2)/(1+y^2)]` `= tan 1/2 [2tan^(-1) x + 2tan^(-1) y]` `= tan[tan^(-1) x + tan^(-1) y]` `= tan[tan^(-1) ((x+y)/(1-xy))]` `= (x+y)/(1-xy)`

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