Measuring Angles in Triangles

Section 4.2

Warm Up

1. Find the measure of exterior DBA of BCD, if mDBC = 30°, mC= 70°, and mD = 80°.

2. What is the complement of an angle with measure 17°?

The sum of the measures of the angles in a triangle is 180 degrees.

An Exterior angle is formed by one side of a triangle and the extension of another side.

The Remote Interior angles are the interior angles NOT adjacent to the exterior angle.

The measure of an exterior angle is equal to the sum of the measures of the two remote interior angles.

Find x and m∠B.

Find the m∠A

B

A C

Find mB.

Find mACD.

Find mK and mJ.

Find the measure of each missing angle.

AB ┻ BC, find the measure of each missing angle.

Find each missing angle.

Lesson Quiz: Part I

1. Find mABD. 2. Find mN and mP.

Lesson Quiz: Part II

3. The diagram is a map showing John's house, Kay's house,

and the grocery store. What is the angle the two houses

make with the store?