Respuesta :

sum of two angles of triangle are equal to the exterior angle of triangle

Answer:

Below.

Step-by-step explanation:

a + b + c = 180 degrees        (angles in a triangle)

c + d = 180 degrees              ( adjacent angles).

So, subtracting the 2 equations:

a + b + c - c - d = 0

a + b - d = 0

a + b = d.