Theorems 2-3 To 2-6

Question 1

Theorem 2-3

Answer 1

Vertical angles are congruent.

Question 2

Theorem 2-4

Answer 2

If two lines are perpendicular, then they form congruent adjacent angles.

Question 3

Theorem 2-5

Answer 3

If two lines form congruent adjacent angles, then the lines are perpendicular.

Ex. If 4 adjacent angles = 180 then they each are 90 degrees and have to result from an intersection of perpendicular lines.

Theorem 2-5 is the true converse of Theorem 2-4.

Question 4

Theorem 2-6

Answer 4

If the exterior sides of the two adjacent acute angles are perpendicular; then the angles are complementary.