How do you verify sin^2 - cos^2 = 2sin^2 theta - 1? Trigonometry Trigonometric Identities and Equations Proving Identities 1 Answer Nghi N. Jul 6, 2015 Verify trig identity Explanation: sin^2 x - cos^2 x = - cos 2x = - (1 - 2sin^2 x) = 2sin^2 x - 1 Answer link Related questions What does it mean to prove a trigonometric identity? How do you prove \csc \theta \times \tan \theta = \sec \theta? How do you prove (1-\cos^2 x)(1+\cot^2 x) = 1? How do you show that 2 \sin x \cos x = \sin 2x? is true for (5pi)/6? How do you prove that sec xcot x = csc x? How do you prove that cos 2x(1 + tan 2x) = 1? How do you prove that (2sinx)/[secx(cos4x-sin4x)]=tan2x? How do you verify the identity: -cotx =(sin3x+sinx)/(cos3x-cosx)? How do you prove that (tanx+cosx)/(1+sinx)=secx? How do you prove the identity (sinx - cosx)/(sinx + cosx) = (2sin^2x-1)/(1+2sinxcosx)? See all questions in Proving Identities Impact of this question 2320 views around the world You can reuse this answer Creative Commons License