There is a base-quadrilateraled pyramid ABCDS , which base is quadrilateral ABCD. Inscribed sphere is tangent in point P on the ABCD wall. Proof that(adsbygoogle = window.adsbygoogle || []).push({});

<)APB+<)CPD=180'

I don't like geometry and i really don't know how to start.

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# Tangent, sphere, pyramid

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