Math 8: Triangles and Angle Measures
Section #6: Finding Measures of Angles Algebraically
Corresponds with Module 2, Lesson 12
Notes # 38
Example#1: In 1 – 2, two parallel lines AB and CD are cut by transversal EF at G
and H respectively.
E
A
G
C
H
B
D
F
a) If m< EGA = 5x – 12 and m< DHF = 3x + 30, then find x.
b) If m< EGB = 3x – 10 and m< GHC = 2x + 40, then find the degree measure of
each angle.
You Try:
In 1 – 2, two parallel lines AB and CD are cut by transversal EF at G and H
respectively.
E
A
G
C
H
B
D
F
1) If m< CHE = 8x - 7 and m< BGE = 3x + 22, then find x.
2) If m< AGF = 6x - 26 and m< CHF = x + 24, then find the degree measure of
each angle.
Example#2
a) Two parallel lines are cut by a transversal. The degree measures of two
alternate interior angles can be represented by the expressions 4x and 2x + 30.
Find the measure of the angles.
b) If the m< FHD is 20 more than 3 times the measure
of < EGB, find the measure of the angles.
A
E
G
C
B
D
H
F
You Try
3) Two parallel lines are cut by a transversal. The degree measures of two
corresponding angles can be represented by the expressions 4x + 10 and 6x - 20.
Find the measure of the angles.
4) If the m< CHG is 15 less than 4 times the measure
of < AGH, find the measure of the angles.
A
C
E
G
H
F
B
D
Geometry
Math 8
________________________
Parallel Lines & Algebra
In 1-5, name each pair of angles as either; adjacent, vertical, corresponding, alternate interior,
or alternate exterior.
1) AGF & HGB
F
G
B
A
2) BGH & CHG
3) CHE & CHG
C
D
H
4) FGB & GHD
5) AGF & EHD
E
Angles found may not match the picture.
6) If m< HGB = 8x – 20 and m< GHD = 2x + 40, then find x.
7) If m< CHG = 8x – 6 and m< HGB = 5x + 12, then find m< HGB.
8) If m< AGF = 5x + 8 and m< CHE = 9x + 18, then find the degree measure of both angles.
Geometry
Math 8
HW #61
Section #6: Parallel Lines and Algebra
Name each pair of angles as either; adjacent, vertical, corresponding, alternate interior, or
alternate exterior.
1) CGH & FHG
2) GHE & EHB
3) AGD & GHF
4) FHB & EHG
C
A
E
G
H
5) AGC & BHF
6) EHB & AGD
7)  EHB & CGH
8)  DGH & GHE
D
Using the figure to the right to answer 9 – 11.
F
1
9) If m5 = 5x and m3 = x, find x.
3
5
7
B
2
4
6
8
Angles found may not match the picture.
10) If m2 = 6x – 10 and m6 = 4x,
Find m2.
11) If m7 = 11x + 12 and m1 = 6x + 15,
find the degree measure of both angles