# Lesson Plan: Corollaries of Isosceles Triangle Theorems Mathematics

This lesson plan includes the objectives and prerequisites of the lesson teaching students how to use the corollaries of the isosceles triangle theorems to find missing lengths and angles in isosceles triangles.

#### Objectives

Students will be able to

- understand that the median of an isosceles triangle from the vertex angle is a perpendicular bisector of the base,
- understand that the bisector of the vertex angle of an isosceles triangle is a perpendicular bisector of the base,
- understand that the straight line that passes through the vertex angle of an isosceles triangle and is perpendicular to the base bisects the base and the vertex angle,
- use the corollaries of the isosceles triangle theorems to solve problems,
- understand that the axis of symmetry of an isosceles triangle is the median that bisects the base.

#### Prerequisites

Students should already be familiar with

- identifying isosceles triangles,
- equilateral triangles,
- congruent triangles,
- the isosceles triangle theorems,
- the Pythagorean theorem.