Trigonometrymedium · Past Paper
What is the value of 1 - 2 sin² 22.5°?
A1/2
B1/√2
C√3/2
D1
✓ Correct Answer: B — 1/√2
This is the form of cos 2θ. So, cos(2 * 22.5°) = cos 45° = 1/√2.
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