The indirect proof of the statement Vertical angles are cong

The indirect proof of the statement “Vertical angles are congruent” begins with the assumption that...

(A) two angles are not vertical

(B) two angles are vertical
(C) two angles are not congruent

(D) two angles are congruent

Solution

To prove that vertical angles are congruent we can take assumption that the other two angles are congruent.

Because in Triangle if two angles are equal then remaining other angles will also be equal as sum of all angles is 180 degrees.

Therefore option D.