Question 9
The side $BC$ of the triangle $ABC$ is extended beyond $C$ to $D$ so that $CD = BC$. The side $CA$ is extended beyond $A$ to $E$ so that $AE = 2CA$.
Prove that if $AD = BE$, then the triangle $ABC$ is right-angled.
Prove that if $AD = BE$, then the triangle $ABC$ is right-angled.