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Notes 2.1B
Geometry
Chapter 3
Angles formed by two intersecting lines,
Parallel and Perpendicular Lines
Angle Pairs We must Know:
Name ___________________________
1) Vertical angles
2) Linear Pair Angles
3) Corresponding Angles
Vertical angles are congruent.
Linear pairs are supplementary.
Looks like the letter “X” in the alphabet.
Two angles that add up to 1800.
If two lines are parallel and cut by a
transversal, then corresponding angles are
congruent
Looks like the letter “F”. in the alphabet.
Looks like the letter “T” in the alphabet.
4) Alternate Interior Angles
5) Alternate Exterior Angles
6) Same-Side Interior Angles
Alternate interior angles are congruent, if
the lines are parallel.
Alternate exterior angles are congruent, if
the lines are parallel.
Same-side interior angles are
supplementary, if the lines are parallel.
Looks like the letter “Z” or “N” in the
alphabet.
Looks like the letter “C” in the alphabet.
7) Complementary Angles
8) Supplementary Angles
9) Perpendicular Angles
Any two angles that add up to 900.
Any two angles that add up to 1800.
Two lines that intersect to form 900 or right
angles.
150
650
750
1150
10) Midpoint
The point that divides(bisects) a segment
into two congruent segments.
M is the midpoint of
11) Angle bisector
A ray that divides (bisects) an angle into
two congruent angles.
K
AC .
R
A
M
C
12) Perpendicular Bisector of a Segment
A line perpendicular to a segment at the
segments midpoint. The point at which it
divides (bisects) the segment into two
congruent segments.
f
L
A
AM + MC = AC Segment Addition
Formula:
 x  x y  y2 
M 1 2 , 1

2 
 2
C
H
LR bisects KLH
mKLH = mRLH + mKLR
Angle Addition
Line f
AC
is the perpendicular bisector of