Q. 2 B5.0( 5 Votes )

Let us show that:

cos257° + cos233° = 1

Answer :

Given, cos257° + cos2 33°


Need to prove the given equation as one


we know that cos(90 - θ) = sinθ


cos33° = cos(90 - 57)°


= sin57° - - - eq (1)


Substitute eq(1) in the given equation


cos257° + sin257°


we know that, sin2θ + cos2θ = 1


cos257° + sin257° = 1


Hence, proved


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