Question

Prove that the sum of two opposite interior angles on triangle is equal to the exterior angle

Answer 1

let the triangle be ABC where
ang.A is 45
ang.B is 90
ang C is 45

ext.ang.B =180-90=90
int.ang opposite to it are angs.A&C
ang.A+ang.C=ext.ang.B
45+45=90
90=90

hence proved