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°.
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