Question

please help!
Prove the triangle exterior angle theorem
The measure of each exterior angle of a triangle equals the sum of the measures of its two remote interior angles
Given: <1 is an exterior angle of the triangle
Prove: m<1 = m,2 + m<3
Shape will be provided below.

Answer 1

m1 and m4 is supplementary, so m1+m4=180degrees, or m1 = 180-m4
then the sum all angle of triangle is 180deg, gives
m2+m3+m4=180 or
m2+m3=180-m4 (remember just new, that 180-m4=m1)
so, m2+m3=m1
proof

Answer 2

Thank you!!

Answer 3

welcome