Find angle of triangle within an isosceles triangle

Question

All i know is that the top left angle is 80 degrees.

Do you know any trigonometry? The law of cosines, for instance? — Arthur, Jan 03 '20 at 10:14

score 0 · Answer 1 · answered Jan 03 '20 at 11:01

0

This is famous problem. I borrowed a picture. $\angle BDC=30$ degree.

answered Jan 03 '20 at 11:01

Takahiro Waki

1 Answers1