Question

prove that the sum of all interior angles of a triangle is equal to 180 degree

Answer 1

hello frnd here is Ur answer

DATA - ∆ PQR
CONSTRUCTION - CONSTRUCT AB PARALLEL TO RQ

TO PROVE - angle 1 + angle 2 + angle 3 = 180°

ANGLE
2 = 4 alternate angles
3 = 5 alternate angles

PROOF - angle 4 + angle 1 + angle 5 = 180°. (linear pair of angles)

angle 4 + angle 1 + angle 5 = 180°
angle 2 + angle 1 + angle 3 = 180°
angel 1 + angel 2 + angel 3 = 180°

hence proved