MathDB

2

Part of 2023 South Africa National Olympiad

Problems(1)

Cyclic quad

Source: The South African Mathematical Olympiad Third Round 2023 P2

7/30/2023
ABCDABCD is a cyclic quadrilateral with ∠BAD=90∘\angle BAD=90^\circ and ∠ABC>90∘\angle ABC>90^\circ. ABAB is extended to a point EE such that ∠AEC=90∘\angle AEC=90^\circ.If AB=7,BE=9,AB=7,BE=9, and EC=12EC=12,calculate ADAD.
geometrycyclic quadrilateral