How do you show that the equation 1-sinx=cosx1−sinx=cosx is not an identity? Trigonometry Trigonometric Identities and Equations Proving Identities 1 Answer Bdub Nov 12, 2016 Pick a value for x like pi/3π3 and plug it in to both side to show that they don't equal each other and therefore not an identity 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 10861 views around the world You can reuse this answer Creative Commons License