2.5 - 2.6 Theorems

Question 1

If AB is perpendicular to CD then <3 =~ <4 (adjacent)

Answer 1

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

Question 2

If <1 =~ <2 (adjacent) then AB is perpendicular to BC

Answer 2

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

Question 3

If AB is perpendicular to CD then <1 and <2 are complementary angles

Answer 3

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

Question 4

If AB is perpendicular to BC then < ABC is a right angle

Answer 4

Definition of perpendicular lines

Question 5

If angle ABC is a right angle, then mABC = 90

Answer 5

Definition of right angle

Question 6

<4 is =~ to <5 (Vertical Angles)

Answer 6

Vertical angles are congruent

Question 7

If <1 and <2 are complementary angles, m<1 + m<2 = 90

Answer 7

Definition of complementary angles

Question 8

If ABC and DEF are supplements, then ABC + DEF = 180

Answer 8

Definition of supplementary angles

Question 9

If <1 and <2 are complements and <3 and <2 are complements,

Answer 9

If 2 angles are complemtary to the same angle, they are congruent

Question 10

<1 =~ <2 <1 + <3 = 180 <2 + <4 = 180

Answer 10

If 2 angles are supplementary to congruent angles, then those angles are complementary

Question 11

If parallel lines are cut by a transversal…

Answer 11

Correspong angles are congruent
Alternate interior angles are congruent
Same side interior angles are supplementary

Question 12

If a transversal is perpindicular to one of two parallel lines,

Answer 12

then it is perpindicular to the other line also