alleryIf sin θ + cos θ = 1, then sin θ × cos θ equals:
A1/2
B1
C-1/2
D0
Answer & Solution
Correct answer: D. 0
Square both sides: (sin θ + cos θ)² = 1
→ sin²θ + cos²θ + 2 sinθ cosθ = 1
We have → 1 + 2 sinθ cosθ = 1 → sinθ cosθ.
So → 1 + 2 sinθ cosθ = 0.
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