PARALLEL LINES ANGLE PROPERTIES VERTICALLY OPPOSITE ANGLES Vertically opposite angles are the same. From the above diagram, angle TRS= angle PRQ=40∘ ANGLES IN A TRIANGLE Angles in a triangle add up to 180 angle QPR+ angle PRQ+ angle PQR=180 angle QPR=68∘ angle PRQ=40∘ 68+40+PQR=180 108+PQR=180 PQR=180−108 PQR=72∘