The point

is inside the convex quadrilateral
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, such that
Prove that
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and
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The point $M$ is inside the convex quadrilateral $ABCD$, such that $$MA = MC,\hspace{0,2cm}\widehat{AMB} = \widehat{MAD} + \widehat{MCD} \quad \textnormal{and} \quad \widehat{CMD} = \widehat{MCB} + \widehat{MAB}\text{.}$$
Prove that $AB \cdot CM = BC \cdot MD$ and $BM \cdot AD = MA \cdot CD.$