How do you prove #cosX / (secX - tanX) = 1 + sinX#? Trigonometry Trigonometric Identities and Equations Proving Identities 1 Answer sankarankalyanam Mar 11, 2018 As below. Explanation: To prove #cos x / (sec x - tan x) = (1 + sin x)# L H S # = cos x / ((1/cos x) - (sin x / cos x)# as #color(blue)(sec x = 1/cos x, tan x = sin x / cos x# #=> cos x / ((1 - sin x) / cos x)# as #color(green)(cos x # is the L C M of Denominator. #=> cos^2 x / (1 - sin x)# #=> = (1 - sin^2 x) / (1 - sin x)# as #color(blue)(cos^2x = 1 - sin^2x# #=> ((1+ sin x) *color(red)(cancel (1 - sin x))) /color(red)(cancel (1 - sin x))# #=> 1 + sin x# Q E D 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 25845 views around the world You can reuse this answer Creative Commons License