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Question
Evaluate:
sin 27° sin 63° – cos 63° cos 27°
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Solution
sin 27° sin 63° – cos 63° cos 27°
= sin (90° – 63°) sin 63° – cos 63° cos (90° – 63°)
= cos 63° sin 63° – cos 63° sin 63°
= 0
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