Problem:
In the figure, △ABC has a right angle at C and LA=20∘. If BD is the bisector of ∠ABC, then ∠BDC=
Answer Choices:
A. 40∘
B. 45∘
C. 50∘
D. 55∘
E. 60∘
Solution:
Since ∠C=90∘ and ∠A=20∘, we have ∠ABC=70∘. Thus ∠DBC=35∘. It follows that ∠BDC=90∘−35∘=55∘.