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Lesson Plan: The Cosine Ratio Mathematics
This lesson plan includes the objectives, prerequisites, and exclusions of the lesson teaching students how to find missing lengths and angles in a triangle using the cosine ratio.
Objectives
Students will be able to
- use right triangles to find cosine ratios,
- use special right triangles to find the cosine ratios for , , and ,
- use the cosine ratio to find missing lengths in right triangles,
- use the inverse cosine ratio to find missing angle measures in right triangles,
- solve more complex problems, such as using the cosine ratio or inverse cosine ratio in combination with the Pythagorean theorem, simple 2D shape properties, or coordinate geometry.
Prerequisites
Students should already be familiar with
- right triangles,
- the Pythagorean theorem,
- simple 2D shape properties,
- coordinate geometry.
Exclusions
Students will not cover
- nonright triangles,
- the graph of the cosine function,
- the secant ratio.
