A challenging geometry problem

by luimichael, Apr 11, 2017, 1:01 PM

As shown in the figure, $\angle ABD=20^\circ$,$\angle DBC=60^\circ$,$\angle DCA = 50^\circ$,$\angle ACB=30^\circ$.
Determine $\angle ADC$
Solution by Trigonometry
Still don't know how to solve this problem by Geometry.

Edit: Problem already solved by sunken rock
See https://artofproblemsolving.com/community/c4h1427621_without_using_trigonometry
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This post has been edited 2 times. Last edited by luimichael, Apr 12, 2017, 12:11 AM
Reason: Update

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