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Question
Prove that:
sin θ cos (90° - θ ) + sin (90° - θ) cos θ = 1
Solution
LHS = sin θ cos (90° - θ) + sin (90° - θ) cosθ
= sin θ sin θ + cos θ cos θ
= sin2 θ + cos2 θ
= 1
= RHS
Hence proved.
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