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Question
Prove that sin(30° + θ) + cos(60° + θ) = cos θ
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Solution
sin(30° + θ) + cos(60° + θ) = cos θ
sin(30° + θ) + cos(60° + θ)
= sin 30° cos θ + cos 30° sin θ + cos 60° cos θ – sin 60° sin θ
= `1/2 cos theta + sqrt(3)/2 sin theta + 1/2 cos theta - sqrt(3)/2 sin theta`
= cos θ
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