Question 13
In the diagram, $ABC$ is a right-angled triangle at $A$ and $\angle ABC=60^\circ$. On side $AC$, point $D$ is taken such that $\angle ABD=20^\circ$. On ray $BD$, point $K$ is taken such that $DK=BC$. What is the measure, in degrees, of $\angle KCB$?
