Question

Angle Theorems for triangles

Answer 1

Explanation:

The interior angles of a triangle add to 180°:a + b + c = 180°

Angles c and d make a straight angle, which is 180°:d + c = 180°

So d + c equals a + b + c:d + c = a + b + c.

Subtract c from both sides:d = a + b.