Trigonometrymedium · Past Paper
Value of cos 75° using compound angle formula is:
A(√3 + 1) / 2√2
B(√3 - 1) / 2√2
C1 / 2√2
D(√3 - 1) / √2
✓ Correct Answer: B — (√3 - 1) / 2√2
cos(45+30) = cos 45 cos 30 - sin 45 sin 30 = (1/√2)(√3/2) - (1/√2)(1/2) = (√3-1)/2√2.
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