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Question

If sin theta=-0.53, find cos(pi/2-theta)

Answer 1

cos(∏/2 - θ)=sinθ, so if sinθ=-0.53, then cos(∏/2 - θ)=-0.53

if you are looking for θ, then use arcsin to get -32.00545483º or 327.994545º; either angle puts you in Q4

Answer 2

Use the identity

 

cos(π/2 - θ) = sinθ

 

sinθ = -0.53

 

Therefore,

 

cos(π/2 - θ) = -0.53