Download Perpendicular Lines

Perpendicular Lines
Lesson 2.5
Geometry Honors
Page 56
Objective:
Lesson Focus
The focus of this lesson is the study and use of
three theorems about perpendicular lines.
Such lines intersect to form right angles.
Perpendicular Lines
Two lines that intersect to form right angles (90 angles.)
Symbol: 
Example:
If AB is perpendicular to CD , then each angle formed
is 90.
C
AB  CD
A
B
D
Perpendicular Lines
Theorem 2-4
If two lines are perpendicular, then they form congruent
adjacent angles.
C
A
B
D
Perpendicular Lines
Theorem 2-5
If two lines form congruent adjacent angles, then the lines are
perpendicular.
C
A
B
D
Perpendicular Lines
Theorem 2-6
If the exterior sides of two adjacent acute angles are
perpendicular, then the angles are complementary.
C
E
A
B
D
Review Quiz
Complete with always, sometimes, or never.
1. Perpendicular lines _____ lie in the same plane.
2. Two lines are perpendicular if and only if they _____ form
congruent adjacent angles.
3. Perpendicular lines _____ form 60 angles.
4. If exterior sides of two adjacent angles are perpendicular,
then the angles are _____ supplementary.
5. If a pair of vertical angles are supplementary, the lines
forming the angles are _____ perpendicular.
Review Quiz
Complete with always, sometimes, or never.
1. Perpendicular lines sometimes lie in the same plane.
2. Two lines are perpendicular if and only if they always form
congruent adjacent angles.
3. Perpendicular lines never form 60 angles.
4. If exterior sides of two adjacent angles are perpendicular,
then the angles are never supplementary.
5. If a pair of vertical angles are supplementary, the lines
forming the angles are always perpendicular.
Homework
Pages 58 - 60
Problems
4 – 24 even, 25 - 29