Question

if a transversal intersects two parallel lines prove that internal bisectors of the angle on the same side of a transversal meet at right angle

Answer 1

that's too easy see in class 8 text book chapter lines and angles

Answer 2

x+y=180
given internal bisectors of the angle is x/2 and y/2
x/2+y/2+z=180
x+y/2+z=180
180/2+z=180
90+z=180
z=90
hence proved