F.2 Similar triangle問題20分

You can use three angles equal for this method.

Angle ABC = Angle CAD (given)
Angle ACD = Angle ACB (common angle)'
So, triangle ABC ~ triangle ACD (three angles equal)

I hope I can help you. ^.^

By angle sum of triangle, the remaining angles found should also be equal.
Hence AAA is correct.

(hey,not "So, triangle ABC ~ triangle ACD (AA)"?)