1 / 11

# Pairs of Angles - PowerPoint PPT Presentation

Pairs of Angles. Geometry (Holt 1-4) k.Santos. Adjacent Angles. Adjacent angles—two angles in the same plane (coplanar) with a common vertex , a common side but no common interior points A D B C < ABD and <DBC are adjacent angles.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Pairs of Angles

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

## Pairs of Angles

Geometry (Holt 1-4)k.Santos

Adjacent angles—two angles in the same plane (coplanar) with a common vertex, a common side but no common interior points

A

D

B C

< ABD and <DBC are adjacent angles

### Linear Pair

Linear Pair—a pair of adjacent angles whose noncommon sides are opposite sides

1 2

< 1 and < 2 form a linear pair

### Complementary Angles

Complementary Angles—two angles whose measures have a sum of 90

A D

30 60

B C

Complementary complementary

<ABD and <DBC30= 90

### Example---Complementary angles

Given: m< 1 =3x + 7 and m < 2= 7x + 3. Find x, m< 1 and m < 2. The angles are complementary.

The angles are complementary

m< 1 + m < 2 = 90

3x + 7 + 7x + 3 = 90

10x + 10 = 90 1 2

10x = 80

x= 8

m<1= 3x + 7 m < 2 =7x + 3

m<1= 3(8) + 7 m< 2 = 7(8) + 3

m< 1 = 31 m < 2 =59

check: 31 + 59 = 90 which are complementary

### Supplementary Angles

Supplementary Angles—two angles whose measures have the sum is 180

1 2 110 70

Supplementarysupplementary

m<1 + m < 2 = 180110 = 180

### Example—Supplementary Angles

Given m< 2 = 125Find the m< 1:

This is a linear pair

So the angles are supplementary

(which means they add to 1802

1

m< 1 + m< 2 = 180

x + 125 = 180

x = 55

So m<1 = 55

### Complements and Supplements

If you have an angle X

It’s complement can be found by subtracting from 90

or (90 – x)

It’s supplement can be found by subtracting from 180

or (180 - x)

### Example—Supplements and Complements

Given: m <A = 72and m <B = (4x – 12)

Find the complement and supplement of <A.

Complement: 90 – 72 = 18 (or 72 + x = 90)

Supplement: 180 – 72 = 108 (or 72 + x = 180)

Find the complement and supplement of <B.

Complement: 90– (4x -12)

90 – 4x + 12

(102 – 4x)

Supplement: 180 – (4x -12)

180 – 4x + 12

(192 – 4x)

### VerticalAngles

Vertical angles—two angles whose sides form two pairs of opposite rays

13

24

Picture always looks like an X

< 1 and < 4 are vertical angles

< 2 and < 3 are vertical angles

### Example—Identifying angle pairs

Name a pair of each of the

following angles: E F

Complementary angles: D