How do you prove (cos^4x - sin^4x)/sin^2x=cot^2x-1cos4x−sin4xsin2x=cot2x−1? Trigonometry Trigonometric Identities and Equations Proving Identities 1 Answer Nghi N. Dec 5, 2015 Prove trig equation. Explanation: cos^4 x - sin^2 x = (cos ^2 x - sin^2 x( (cos^2 x + sin^2 x) = cos4x−sin2x=(cos2x−sin2x((cos2x+sin2x)= = (cos@ x - sin^2 x).=(cos∘x−sin2x). because (cos^2 x + sin^2 x) = 1 (cos^2 x - sin^2 x)/(sin^2 x) = cos^2 x/(sin^2 x) - sin^2 x/(sin^2 x) = cos2x−sin2xsin2x=cos2xsin2x−sin2xsin2x= = cot^2 x - 1=cot2x−1 Answer link Related questions What does it mean to prove a trigonometric identity? How do you prove \csc \theta \times \tan \theta = \sec \thetacscθ×tanθ=secθ? How do you prove (1-\cos^2 x)(1+\cot^2 x) = 1(1−cos2x)(1+cot2x)=1? How do you show that 2 \sin x \cos x = \sin 2x2sinxcosx=sin2x? is true for (5pi)/65π6? How do you prove that sec xcot x = csc xsecxcotx=cscx? How do you prove that cos 2x(1 + tan 2x) = 1cos2x(1+tan2x)=1? How do you prove that (2sinx)/[secx(cos4x-sin4x)]=tan2x2sinxsecx(cos4x−sin4x)=tan2x? How do you verify the identity: -cotx =(sin3x+sinx)/(cos3x-cosx)−cotx=sin3x+sinxcos3x−cosx? How do you prove that (tanx+cosx)/(1+sinx)=secxtanx+cosx1+sinx=secx? How do you prove the identity (sinx - cosx)/(sinx + cosx) = (2sin^2x-1)/(1+2sinxcosx)sinx−cosxsinx+cosx=2sin2x−11+2sinxcosx? See all questions in Proving Identities Impact of this question 8262 views around the world You can reuse this answer Creative Commons License