If cos A / a = cos B / b = cos C / c, then triangle ABC... – Trigonometry

Trigonometryhard · Past Paper

If cos A / a = cos B / b = cos C / c, then triangle ABC is:

AIsosceles

BRight angled

CEquilateral

DScalene

✓ Correct Answer: C — Equilateral

Combining with sine rule (a/sin A), this implies tan A = tan B = tan C, so A=B=C=60°.

Share this question