Trigonometrymedium · Past Paper
If A + B = 45°, what is (1 + tan A)(1 + tan B)?
A1
B2
C3
D4
✓ Correct Answer: B — 2
tan(A+B) = 1 implies (tan A + tan B) / (1 - tan A tan B) = 1. Expanding (1+tan A)(1+tan B) = 1 + tan A + tan B + tan A tan B = 1 + (1 - tan A tan B) + tan A tan B = 2.
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