Trigonometryhard · Past Paper

Simplify: √( (1 - cos A) / (1 + cos A) ).

Atan(A/2)
Bcot(A/2)
Csin(A/2)
Dcos(A/2)

✓ Correct Answer: Atan(A/2)

1 - cos A = 2 sin²(A/2) and 1 + cos A = 2 cos²(A/2). The ratio is tan²(A/2), and root gives tan(A/2).

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