CLASSIFYING ANGLES

MEAP REVIEW

Degrees: Measuring Angles

We measure the size of an angle using degrees. Example: Here are some examples of angles and their degree measurements.

Acute Angles

An acute angle is an angle measuring between 0 and 90 degrees.

Example:

                                                             

  

Obtuse Angles

An obtuse angle is an angle measuring between 90 and 180 degrees.

Example:

                                                              

   

Right AnglesA right angle is an angle measuring 90 degrees.

Examples:

                                      

Complementary AnglesTwo angles are called complementary angles if the sum of their degree measurements equals 90 degrees.

Example:

These two angles are complementary.

                                                      

                        

These two angles can be "pasted" together to form a right angle!

                        

Supplementary AnglesTwo angles are called supplementary angles if the sumof their degree measurements equals 180 degrees.

Example:

These two angles are supplementary.

                                                                      

These two angles can be "pasted" together to form a straight line!

                                                

Vertical Angles

For any two lines that meet, such as in the diagram below, angle AEB and angle DEC are called vertical angles. Angle BEC and angle AED are also vertical angles. Vertical angles have the same degree measurement.                                    

Review

State whether the following are acute, right, or obtuse.1.

2.

3.

4.

5.

??

acute obtuseright

obtuseacute

Complementary and Supplementary

1. Two angles are complementary. One measures 65 degrees.

2. Two angles are supplementary. One measures 140 degrees.

Find the missing angle.

Answer : 25

Answer : 40

Complementary and Supplementary

Find the missing angle. You do not have a protractor.Use the clues in the pictures.

1.2.x

55 165x

X=35 X=15

Vertical Angles

Find the missing angle. You do not have a protractor.

Use the clues in the pictures.

58x

X=58

Transversals

A transversal crosses two or more lines at different points:

• Interior angles are on either side of a transversal between a pair of lines.

• Exterior angles are on either side of a transversal outside of a pair of lines.

Angles 3,4,5, and 6 are interior angles.

Angles 1,2,7, and 8 are exterior angles.

More drawings

20

C

J

D

E F

G

H

70

9070

20

90

Final Drawing

52

B

A

F E

D

C

60

G

68

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