Trigonometryhard · Past Paper
Evaluate: cos 12° + cos 84° + cos 132° + cos 156°.
A1/2
B-1/2
C1
D0
✓ Correct Answer: B — -1/2
Pairing terms (12, 132) and (84, 156) and using 2 cos A cos B formulas results in -1/2.
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