Solve the following question using an appropriate Euclid's axiom:
In the figure,we have $\angle 1 = \angle 2$ and $\angle 2 = \angle 3$. Show that $\angle 1 = \angle 3$.

(N/A) We are given:
$\angle 1 = \angle 2$ (Given)
$\angle 2 = \angle 3$ (Given)
According to Euclid's first axiom,"Things which are equal to the same thing are equal to one another."
Since both $\angle 1$ and $\angle 3$ are equal to $\angle 2$,it follows that $\angle 1 = \angle 3$.