Trigonometryhard · Past Paper
Evaluate: sin^2 5 + sin^2 10 + ... + sin^2 90.
A8.5
B9
C9.5
D10
✓ Correct Answer: C — 9.5
Pairs like sin^2 5 + sin^2 85 = 1. There are 8 such pairs, plus sin^2 45 (0.5) and sin^2 90 (1). Total = 8 + 0.5 + 1 = 9.5.
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