Trigonometrymedium · Past Paper
If cos A = 4/5, find tan(A/2).
A1/2
B1/3
C2/3
D1/4
✓ Correct Answer: B — 1/3
tan(A/2) = sqrt((1-cosA)/(1+cosA)) = sqrt((1/5)/(9/5)) = sqrt(1/9) = 1/3.
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