1. Pairs of Angles If m DEF = 73º, find the measure of its supplement.
COURSE 3 LESSON 8-1
Pairs of Angles
If m DEF = 73º, find the measure of its supplement.
x° + m DEF = 180°
The sum of the measures of supplementary angles is 180º.
x° + 73° = 180°
Substitute 73º for m DEF.
x° + 73° – 73° = 180° – 73°
Subtract 73º from each side.
x° = 107°
Simplify.
The measure of the supplement of m DEF is 107º.
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2. COURSE 3 LESSON 8-1
Pairs of Angles
A right angle is divided into two angles. If the measure of the larger angle is 67°, find the measure of its complement.
x° + 67° = 90°
The sum of the measures of complementary angles is 90º.
Subtract 67º from each side.
x° + 67° – 67° = 90° – 67°
x° = 23°
Simplify.
The measure of the complement of 67º is 23º.
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3. COURSE 3 LESSON 8-1
Pairs of Angles
In this figure, if m DKH = 73°, find the measures of GKJ and JKF.
m DKE + 90° = 180°
DKE and FKE are supplementary.
m DKE = 90°
Subtract 90º from each side.
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4. Pairs of Angles m KHE + 73° = 90° KHE and DKH are complementary.
COURSE 3 LESSON 8-1
Pairs of Angles
(continued)
m KHE + 73° = 90°
KHE and DKH are complementary.
m KHE = 17°
Subtract 73º from each side.
GKJ and KHE are vertical angles.
m GKJ = m KHE = 17°
JKF and DKH are vertical angles.
m JKF = m DKH = 73°
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5. Pairs of Angles Use the diagram to answer Questions 1 and 2.
COURSE 3 LESSON 8-1
Pairs of Angles
Use the diagram to answer Questions 1 and 2.
1. List all pairs of vertical angles.
2. List any angles adjacent to CXD.
3. If m AXB = 110°, find m DXC.
4. An angle measures 57°. What is the measure of its supplement?
5. An angle measures 24°. What is the measure of its complement?
AXD and BXC; AXB and DXC
AXD and BXC
110°
123°
66°
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