## Elementary Geometry for College Students (6th Edition)

$\angle$RWV= $\angle$SWT (VERTICALLY OPPOSITE ANGLES ARE EQUAL) BY USING SUM OF ANGLES OF A TRIANGLE =$180^{\circ} \triangle$RWV = $\angle$1 + $\angle$2 + $\angle$RWV =180 ......(1) $\triangle$TWS = $\angle$3 + $\angle$4 + $\angle$SWT =180 .....(2) BY COMPARING 1 AND 2 $\angle$1 + $\angle$2 + $\angle$RWV = $\angle$3 +$\angle$4 + $\angle$SWT SINCE $\angle$RWV= $\angle$SWT $\angle$1 + $\angle$2 = $\angle$3 + $\angle$4 HENCE PROVED