Problem : In a triangle $ABC$ with side $AB=AC$ and $\measuredangle BAC=20 ^\circ $.
$D $ is a point on side $AC$ and $BC = AD$. Find $ \measuredangle DBC$
So $ \measuredangle ACB = \measuredangle ABC$
$ \measuredangle ACB = \measuredangle ABC=80^\circ$ (Using angle sum property)
I am unable to continue from here.
Any assistance is appreciated.