Unit 11: Angles + Triangles - Lesson 3

Unit 11: Angles + Triangles

Lesson 3: Side and Angle Relationship of Triangles

Triangle Angle Side

In a Triangle,

The SMALLEST angle is across from the SMALLEST side

The MEDIUM angle is across from the MEDIUM side

The LARGEST angle is across from the LARGEST side

Multiple Select

SELECT ALL statements that are TRUE

• Angle XYZ corresponds with side XZ

• Angle ZYX corresponds with side XY

• Angle ZXY corresponds with side ZY

• Angle YZX corresponds with side YX

Side/Angle Relationship Isosceles

Isosceles triangles have:

2 congruent or EQUAL sides

2 congruent or EQUAL Angles

Solve for Missing Value:

Step 1: Set up Equation and Plug-in

Step 2: Solve

Multiple Choice

Find the value of y

• 100

• 180

• 40

• 50

Multiple Choice

What is the measure of the Top Left Angle.

• 55

• 27.5

• 125

• 110

Multiple Choice

Find the value of x

• 11

• 7

• 4

• 15

Side/Angle Relationship Equilateral

Equilateral Triangles Have:

3 congruent or EQUAL sides

3 congruent or EQUAL angles [60 Degrees]

Solve for Missing Value:

Step 1: Set up Equation and Plug-in

Step 2: Solve

Multiple Choice

Solve for x.

• 5

• 12

• -7

• -6

Multiple Choice

Find the side length x of an Equilateral Angle

• A. 9

• B. 10

• C. 6

• D. 11

Multiple Choice

What is the length of the side x?

[HINT: The bottom length is x+3 so set both sides equal to each other: 10 = x +7, then solve]

• 7

• 3

• 10

• 13