Because ∠ ADB =ACB, ∠ CBD = ∠ ACB = ∠ APB/2 = 20/2 =10.

Because ∠ABD=∠ACD, ∠ABC=∠BCD, you can also get ∠BAD=∠CDA.

Because BC is the diameter of a circle, ∠ BDC = 90, ∠ BCD = 90-∠ CBD = 90- 10 = 80, ∠ CDA =180 = 65438+.

So ∠ ABC = ∠ BCD = 80, ∠ Bad = ∠ CDA = 100.