1975 Canadian MO Problems/Problem 5

Problem 5

$A, B, C, D$ are four "consecutive" points on the circumference of a circle and $P, Q, R, S$ are points on the circumference which are respectively the midpoints of the arcs $AB, BC, CD, DA.$ Prove that $PR$ is perpendicular to $QS$.


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1975 Canadian MO (Problems)
Preceded by
Problem 4
1 2 3 4 5 6 7 8 Followed by
Problem 6

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