Question

Given: angle 1 = angle 4
Prove: angle 2 = angle 3

Answer 1

$\angle 1 = \angle 2 \qquad$ vertical angles

$\angle 3 = \angle 4 \qquad$ vertical angles

$\angle 1 = \angle 4 \qquad$ given

$\angle 2 = \angle 3 \qquad$ transitivity