Trigonometrymedium · Past Paper
Express cos 2A in terms of sin A.
A2 sin² A - 1
B1 - 2 sin² A
C1 + 2 sin² A
Dsin² A - cos² A
✓ Correct Answer: B — 1 - 2 sin² A
cos 2A = cos² A - sin² A = (1 - sin² A) - sin² A = 1 - 2 sin² A.
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