# Lesson Plan: Angles of Intersecting Lines in a Circle Mathematics

This lesson plan includes the objectives, prerequisites, and exclusions of the lesson teaching students how to find the measures of angles resulting from the intersection of two chords, two secants, two tangents, or tangents and secants in a circle.

#### Objectives

Students will be able to

• recall theorems for two or more intersecting chords,
• recall and apply the theorems for two intersecting secants, an intersecting tangent and secant, and two intersecting tangents,
• find unknown angle measures and lengths by applying these theorems,
• solve problems which require the application of multiple theorems, including applied problems which require forming and solving equations.

#### Prerequisites

Students should already be familiar with

• central angles and measures of arcs,
• forming and solving equations,
• inscribed angles,
• the relationships between equal chords and arcs.

#### Exclusions

Students will not cover

• problems that require the use of trigonometry,
• special segments of circles,
• properties of tangent segments to a circle from an external point,
• angles of tangency.