Let ABCD be a tangential quadrilateral and P be the center of the inscribed circle (see the figure below). if S1 = area APB, S2 = area BPC, S3 = area PCD and S4 = area APDH, prove that S1 + S3 = S2 + S4.
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Ten problems: 1411-1420
Tangential or Circumscribed Quadrilateral
Incenter, Inscribed circle
Circle Tangent Line
HTML5 and Dynamic Geometry
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