sin²θ + cos²θ equals:
Acos 2θ
B2
C0
D1
Answer & Solution
Correct answer: D. 1
Pythagorean identity: sin²θ + cos²θ = 1 for all θ. From right triangle x² + y² = r². Sin = y/r, cos = x/r, so sin² + cos² = (x²+y²)/r² = 1.
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