Q. 2 B5.0( 5 Votes )

# Let us show that:cos257° + cos233° = 1

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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