1-4 Pair of Angles
Warm-up
1.BD bisects ABC, mABD =
,
and mDBC = (y + 4)°. Find mABC.
2. mWYZ = (2x – 5)° and mXYW = (3x +
10)°. Find the value of x.
Warm-up answers
 1.BD bisects ABC, mABD =
mDBC = (y + 4)°. Find mABC.
, and
 Answer:32°
 2. mWYZ = (2x – 5)° and mXYW = (3x +
10)°. Find the value of x.
 Answer: 35
Objectives
 Students will be able to:
 * Identify adjacent, vertical, complementary, and
supplementary angles.
 * Find measures of pairs of angles.
1-4 pair of angles
 What is an angle?
 Answer: an angle is a figure formed by two rays with a
common endpoint of vertex.
 What are some of the different types of angles you
have heard?
1-4 pair of Angles
 So today we are going to see different kinds of pair
angles like
 Linear pairs add up to 180
1-4 pair of angles
1-4 Pair of angles
 You can find the complement of an angle that
measures x° by subtracting its measure from 90°, or
(90 – x)°.
 You can find the supplement of an angle that measures
x° by subtracting its measure from 180°, or (180 – x)°.
1-4 Pair of Angles
 Another angle pair relationship exists between two
angles whose sides form two pairs of opposite rays.
Vertical angles are two nonadjacent angles
formed by two intersecting lines. 1 and 3 are
vertical angles, as are 2 and 4.
 Vertical angles are congruent.
1-4 pair of Angles
 Example #1
 Tell whether the following pair of angles are linear,
adjacent , vertical or complementary.
 From the Angle Pair relationship worksheet
 Problem s 1, 2, 5 and 8
 Student Guide 3, 4, 6,7
1-4 Pair of Angles
 Example #2
 From the angle pair worksheet problems 9,10,12
 Student guide 13,14 and 18
1-4 pair of angles
 Example #3
 Angle pair worksheet
Problem 19,20
Student guide 21 and 22
1-4 Pair of angles
 Just Remember complementary add up to 90 and
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supplementary add up to 180.
Example #4
Two angles are complementary. One angle is 4 times the other.
The other angles is x+6. Find the two angles .
Answer:
Angle1+angle 2=90
(x+6)+4(x+6)=90
X+6+4x+24=90
5x+30=90
5x=60
X=12
Angle 1=18, Angle2=72
1-4 pair of angles
 Example #5
 One angle is 5x+3 and its supplementary angle is
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3times the other angle. Find x
Answer:
5x+3+3(5x+3)=180 simplify
5x+3+15x+9=180 combine like terms
20x+12=180
solve for x
20x=168
divide by 20

X=8.4
1-4 pair of angles
 Homework page 32
 Problems # 14, 18,19 ,26,29
 Finish the angle pair worksheet
Closure
 Today we learned about the different pair angles like
linear angles, adjacent angles, vertical angles. We also
learned about complementary and supplementary
angles. Tomorrow we are going to have a quiz and
continue with 1-5 part 1.