Triangle Congruence Introduction

Triangle Congruence Lesson 1

Geometry

Mrs. LaGrange

Key Concept!

We can classify triangles by their sides and angles.

Let's try classifying a few...

Multiple Choice

Which type of triangle is pictured?

• Equilateral Triangle
• Right Isosceles Triangle
• Obtuse Scalene Triangle
• Obtuse Equilateral Triangle

Multiple Choice

Name this triangle

• Acute, Scalene
• Obtuse, Scalene
• Right, Isosceles
• Acute, Equilateral

Multiple Choice

Name this triangle.

• Right, Isosceles
• Scalene, acute
• Isosceles, acute
• Equilateral, obtuse

Theorem:

The sum of the interior angles of a triangle is 180 degrees.

It follows that the acute angles of a right triangle are complementary.

Multiple Choice

The Triangle Sum Theorem states that the sum of all angles in a triangle is ______. 

• 45°
• 90°
• 180°
• 360°

Multiple Choice

Solve for x.

• 16
• 11
• 50
• 6

Multiple Choice

Solve for x.

• 5
• 12
• -7
• -6

Multiple Choice

Find the measure of the missing angle.

• 47

• 57

• 53

• 133

Interior and Exterior Angles

The original angles formed inside the triangle are interior angles. The angles that form linear pairs with the interior angles are exterior angles.

• Note angle a and angle b are sometimes called remote interior angles.

Multiple Choice

Which two angles are the remote interior angles to Angle W?

• Angle X and Angle Y

• Angle X and Angle Z

• Angle Y and Angle Z

• Angle Z and Angle W

Multiple Choice

What is the measure of angle b?

• 36^o
• 56^o
• 63^o
• 117^o

Multiple Choice

Which of the following terms best describes Angle d? 

• Remote interior angle
• Corresponding angle
• Exterior angle
• Interior angle

Multiple Choice

Which of the following angles can you add together to equal angle d? 

• Angle a and Angle b
• Angle b and Angle c
• Angle a and Angle c
• Angle a and Angle b and Angle c