# Lesson Plan: Circles Mathematics • 11th Grade

This lesson plan includes the objectives, prerequisites, and exclusions of the lesson teaching students how to use the properties of a circle and its parts in order to solve problems.

#### Objectives

Students will be able to

• recall the definition of a circle and the different parts of a circle,
• understand that all circles are similar,
• understand the condition required for the congruence of two circles (same radius/diameter),
• understand that any line passing through the center of a circle is a line of reflectional symmetry,
• understand basic relationships between the parts of a circle, such as
• the diameter is twice the radius,
• the diameter passes through the center of a circle,
• a chord divides a circle into a major and minor segment,
• understand that any two radii of a circle and the chord that connects them form an isosceles triangle,
• understand that if chords of the same length connect radii in the same circle (or in congruent circles), then the two isosceles triangles formed are congruent,
• use the basic relationships between the parts of a circle and triangles to find unknown angles or lengths.

#### Prerequisites

Students should already be familiar with

• similarity and congruence,
• semicircles and quarter circles,
• solving linear equations,
• the Pythagorean theorem,
• definitions of the following parts of a circle:
• center,
• diameter,
• circumference,
• chord,
• tangent,
• arc,
• sector,
• minor segment,
• major segment.

#### Exclusions

Students will not cover

• finding the length of the circumference when given the radius or diameter,
• finding the area of a circle,
• the relationship between a radius and a connected tangent (forming a right angle),
• complex circle theorems (such as the arrowhead, bow tie, and alternate segment theorems),
• theorems involving equal chords or parallel chords,
• theorems related to cyclic polygons.