WOLFRAM|DEMONSTRATIONS PROJECT

A Parallelogram with Vertices on Two Circles

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vertical position of O
radius of first circle (gold)
radius of second circle (green)
rotate M
Let a circle have diameter AB and let M be a point on another circle with center at A. Let the circles intersect at C and D. Let BM, CM, and DM intersect the first circle at N, P, and Q, respectively. Then MPBQ is a parallelogram.