Solving for Angle Measures

Finding Unknown Angle Measurements

What do we already know?

Angle ABC = 40 $\degree$  

What else do we know?

Solve for  $\angle$  CBH
90 $\degree$  - 40 $\degree$  = ?

Where did 90 $\degree$ come from? 

90 $\degree$  is the measure of  $\angle$  ABH which is a right angle.

Complementary Angles

are two angles that add up to 90°

Example from the picture to the right: 40° + 50° = 90°

More

Examples: 45° + 45° = 90°

Example: 82° + 8° = 90°

Multiple Choice

Find the measure of $$\angle$$  DEG

• 46 $$\degree$$  

• 36 $$\degree$$  

• 90 $$\degree$$  

• 126 $$\degree$$  

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Multiple Choice

Which pair of angle measurements are complementary?

• 18 $$\degree$$ 72 $$\degree$$

• 50 $$\degree$$ 30 $$\degree$$

• 25 $$\degree$$ 75 $$\degree$$

• 45 $$\degree$$ 35 $$\degree$$

Multiple Choice

What is the measurement of angle a?

• 30 $$\degree$$

• 25 $$\degree$$

• 90 $$\degree$$

• 60 $$\degree$$

Supplementary Angles

Two angles that add up to 180°

Examples: 120° + 60°= 180°

Example: 84° + 96°= 180°

What is the measure of angle a if angle b measures 68 $\degree$  ?

Notice that a and b together equal a straight line.

Multiple Choice

 Find the measure of $$\angle$$  PQS

• 34 $$\degree$$  

• 56 $$\degree$$  

• 146 $$\degree$$  

• 180 $$\degree$$  

Multiple Choice

Angle MNP and Angle PNO have a combined measure of 180 $$\degree$$
The measure of  $$\angle$$  MNP is 87 $$\degree$$  

What is the measure of  $$\angle$$  PNO in degrees?
The measure of  $$\angle$$  PNO is ____________ degrees.

• 87 $$\degree$$  

• 3 $$\degree$$  

• 93 $$\degree$$  

• 103 $$\degree$$  

Multiple Choice

Angle ABC is divided into 2 smaller angles by a ray. One of the smaller angles formed is an obtuse angle and the other is an acute angle. Which of the following could NOT be the measure of angle ABC?

• 79 $$\degree$$

• 93 $$\degree$$

• 107 $$\degree$$

• 119 $$\degree$$

Angles on a Straight Line Add Up to 180

What does angle b equal?

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Multiple Choice

What is the measure of angle KGH 

if angle EGK measures 59 $$\degree$$ ?

The measurement of angle KGH is ______ degrees.

• 59 $$\degree$$  

• 31 $$\degree$$  

• 180 $$\degree$$  

• 121 $$\degree$$  

Multiple Choice

Angle AED and angle DEC are adjacent right angles. Together, they form angle AEC. What type of angle is angle AEC?

• acute

• obtuse

• right

• straight