Trigonometryhard · Past Paper

If tan(A/2) = t, then cos A = ?

A(1-t^2)/(1+t^2)
B2t/(1+t^2)
C2t/(1-t^2)
D(1+t^2)/(1-t^2)

✓ Correct Answer: A(1-t^2)/(1+t^2)

Cosine formula in terms of half-angle tangent.

Share this question

More from Trigonometry