Q3 of 61 Page 204

Prove the following identities.

Consider LHS,


LHS = +


We know that sin (90° - θ) = cosθ and cos (90° - θ) = sinθ.


+ = +


Taking LCM,


+ =


We know that (a + b) (a – b) = a2 – b2.


+ =


We know that 1 –sin2θ = cos2θ.


+ =


= 2 ()


We know that = secθ.


+ = 2secθ = RHS


Hence proved.


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