# Lesson Plan: Inequality in One Triangle: Angle Comparison Mathematics • Second Year of Preparatory School

This lesson plan includes the objectives, prerequisites, and exclusions of the lesson teaching students how to form inequalities involving the measures of angles in a triangle given the lengths of the sides of the triangle.

#### Objectives

Students will be able to

- form inequalities involving the measures of angles in a triangle given some of the angles in the triangle,
- understand that in a triangle, when two sides have unequal length, the angle opposite the longer side is larger than the angle opposite the shorter side,
- form inequalities involving the measures of angles in triangles by comparing the lengths of the sides opposite to each angle,
- prove given inequalities about measures of angles in triangles using opposite sides and axioms of inequalities.

#### Prerequisites

Students should already be familiar with

- axioms of inequalities,
- exterior angles of a triangle,
- parallel lines and traversals,
- the sum of angles in a triangle,
- isosceles triangles.

#### Exclusions

Students will not cover

- the triangle inequality,
- comparing the lengths of the sides of a triangle.