Trigonometryhard · Past Paper
If cos A / a = cos B / b, then the triangle is:
AIsosceles
BEquilateral
CRight-angled
DNone
✓ Correct Answer: A — Isosceles
Using sine rule a/sinA = b/sinB, we get cosA/sinA = cosB/sinB => cot A = cot B => A = B.
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