Angles of Triangles

Angles of Triangles

Angle Sum of a Triangle

• The sum of the measures of the interior angles of a triangle is 180^o.

• <1 + <2 + <3 = 180

Find the missing angle.

In Δ MAY , if m^o and the m^o

Give this a try! The work and answer are on the next slide.

So what is angle A?

• Remember the sum of all three angles is 180.

• m<A = 180 - (72 + 74)

• m<A = 180 - 146

• m<A = 34^o

Here is another example. The measures of the angles of a ΔABC are in the ratio 1:4:5. What are the measures of the angles?

• Let x = angle A

• Then ......4x = angle B and 5x = angle C

• Now we can make a equation! x + 4x + 5x = 180

• 10x = 180

• x = 18

Multiple Choice

Find the missing angle x.

• 145^o

• 90^o

• 35⁰

• 180^o

Please copy this into your notes!

Finding x

Remember the sum of the remote interior angles equals the exterior angle.

So........

63 + 86 = x

149 ^o = x

Finding x when it is a interior angle!

• The sum of the remote interior angles equals the exterior angle.

• x + 40 = 100

• -40 from both sides

• x = 60^o

LETS DO THIS!

Multiple Choice

In a triangle, how many total degrees are there?

• 100%
• 180 degrees
• it varies
• 360 degrees

Multiple Choice

A student is trying to construct triangles using four different sets of angles. The angles in each set are given below. Which set will form a triangle?

• 45°, 65°, 70°

• 150°, 110°, 100°

• 50°, 50°, 50°

• 90°, 90°, 90°

Multiple Choice

Find the measure of the missing angle.

• 90^o

• 10⁰

• 130^o

• 50^o

Multiple Choice

Find the measure of the indicated angle.

• 95

• 85

• 35

• 45

Multiple Choice

The sum of the remote interior angles equals the exterior angle.

Multiple Choice

Which of the following terms best describes Angle d?

• Remote interior angle

• Corresponding angle

• Exterior angle

• Interior angle

Multiple Choice

Find the measure of angle x. Be careful! They did NOT give you two remote interior angles.

• 138

• 96

• 93

• 87

Multiple Choice

Find the measure of the missing angles.

• A

• B

• C

• D

Multiple Choice

Hint: Remeber their sum is 180^o.

• 11

• 25

• 35

• 50

Multiple Choice

If two of the angles of a triangle are 30 and 70 degrees, the third angle measures...

• 80
• 100
• 60
• 90

Multiple Choice

What is the third angle of a triangle whose 1st angle is 34 and 2nd angle is 101?

• 32
• 39
• 45
• 54

Multiple Choice

Find the measure of the indicated angle. 

• 95
• 85
• 35
• 45

Multiple Choice

Find the measure of the indicated angle. 

• 26
• 36
• 85
• 144

Multiple Choice

• x = 118
• x = 108
• x = 28
• x = 58

Multiple Choice

Find the measure of the indicated angle. 

• 180
• 70
• 54
• 56

Multiple Choice

Which Angle measurements does NOT create a Triangle?

• 60,60,60

• 90,45,45

• 50,60,40

• 50,100,30

Multiple Choice

Find <S

• A

• B

• C

• D

Multiple Choice

What is the measure of angle b?

• 36^o
• 56^o
• 63^o
• 117^o

Multiple Choice

Find the measure of the indicated angle. 

• 145
• 113
• 102
• 78