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June 6th, 2019, 08:17 PM   #1
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Help with proof?

The givens are,
Quad ABCD is inscribed inside the circle
Diagonals AC and BD meet at point E.
Line AD is congruent to Line CD

How do you prove that
BE * AD = EC * AB?
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June 7th, 2019, 12:49 AM   #2
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$\small\angle$ADB = $\small\angle$ACB = $\small\angle$ECB and $\small\angle$ABD = $\small\angle$DBC = $\small\angle$EBC.
AB/AD = sin($\small\angle$ADB)/sin($\small\angle$ABD) = sin($\small\angle$ECB)/sin($\small\angle$EBC) = BE/EC.
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