MathNet 2018-part-05 — 181 problems (EN–VI) Question 44

Consider an isosceles triangle $ABC$, where $AB = AC$ and $\angle BAC = 100^\circ$. Let point $D$ on the opposite side from $C$ with respect to $AB$ such that $DC = BC$, and $\angle BCD = 20^\circ$. Find $\angle DAB$.