cos²A-cos²B = sin(A+B)sin(B-A). cos²15°-cos²75° = sin90°·sin60° = 1·(√3/2) = √3/2
The value of cos²15° - cos²75° is:
Verified 30 May 2026.
√3/2
1/2
1/√2
√3/4
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