Browse · MATH Print → jmc geometry intermediate Problem Triangles ABC and ADC are isosceles with AB=BC and AD=DC. Point D is inside △ABC, ∠ABC=40∘, and ∠ADC=140∘. What is the degree measure of ∠BAD? Solution — click to reveal Because △ABC is isosceles, ∠BAC=21(180∘−∠ABC)=70∘. Similarly, ∠DAC=21(180∘−∠ADC)=20∘. Thus ∠BAD=∠BAC−∠DAC=50∘. Final answer 50^{\circ} ← Previous problem Next problem →