Question

if 2 parallel lines are intersected by a transversal, prove that the bisector of the interior angles on the same side of the interior angles on the same side of the transversal line interact each other at right angle

Answer 1

sorry for bad handwriting , and yeah the sum of all angle is 180

Answer 2

Solutions:

We know that the sum of interior angles on the same side of the transversal is 180°.

Hence, ∠BMN + ∠DNM = 180°

=> 1/2∠BMN + 1/2∠DNM = 90°

=> ∠PMN + ∠PNM = 90°

=> ∠1 + ∠2 = 90° ............. (i)

In △PMN, we have

∠1 + ∠2 + ∠3 = 180° ......... (ii)

From (i) and (ii), we have

90° + ∠3 = 180°

=> ∠3 = 90°

=> PM and PN intersect at right angles.