Circles · Class 9 · CBSE Mathematics

If ABCD is a cyclic quadrilateral such that angle A = 80^circ, then the measure of angle C is:

Practice question from Circles (Class 9 · CBSE Mathematics), with the correct answer and a step-by-step solution.

easy · MCQ · Q-4595F5

If ABCDABCD is a cyclic quadrilateral such that ∠A=80∘\angle A = 80^\circ, then the measure of ∠C\angle C is:

  1. A.80°
  2. B.100°Correct answer
  3. C.180°
  4. D.10°

Solution

The opposite angles of a cyclic quadrilateral are supplementary. Therefore, ∠A+∠C=180∘\angle A + \angle C = 180^\circ. Given ∠A=80∘\angle A = 80^\circ, we get ∠C=180∘−80∘=100∘\angle C = 180^\circ - 80^\circ = 100^\circ.

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