1. Perpendicularity of a Line & a Plane
Lesson 6.2

2. Definition:
A line is ⊥ to a plane if it is ⊥ to every line in the plane that passes through its foot. A
AB ⊥ BD C B E D
If AB ⊥ m,
then AB ⊥ BC
AB ⊥ BD and
AB ⊥ BE. m

3. Prove a line ⊥ to a plane
Theorem 48: If a line is ⊥ to two distinct lines that lie in a plane and that pass through the foot, then it is ⊥ to the plane. A C B D m

4. If <STR is a right angle, can you conclude ST ⊥ m ?
NO!!!, to be ⊥ it must be ⊥ to at least 2 lines that lie on m and pass through T

5. PF  k
PF  FG, PF  FH
 PFG is a rt  PFH is a rt 
PG  PH
PF  PF
ΔPFG  ΔPFH
G  H
Given
If a line is  to a plane, it is  to every line in the plane that passes through its foot.
 lines form rt s
Reflexive Property
HL (3,4,5)
CPCTC