Lesson 7: 5-3: Inequalities in One Triangle

1. How do the measures of the sides of a triangle relate to the measures of its angles?
2. How do you know which angles have measures greater than a given exterior angle?

G.CO.10
Prove theorems about triangles

The measure of an exterior angle is greater than the measure of either of its corresponding remote interior angles. If one side of a triangle is longer than another side, then the angle opposite the longer side has a greater measure than the angle opposite the shorter side.

To create the appearance of depth in a room, interior designers use a technique called triangulation. A basic example of this technique is the placement of an end table on each side of a sofa with a painting over the sofa. The measures of the base angles of the triangle should be less than the measure of the other angle.

Students approaching grade level can be given practice problems in small groups to work with other students or directly with the teacher.
Students beyond grade level can make deeper connections by thinking about the types of triangles that wouldn't be possible to list angles and sides from smallest to largest.

Formative Assessment

Textbook in class

Access online textbook and resources through class link.