More Lessons for Trigonometry

Math Worksheets

Videos, worksheets, games and activities to help students learn how to find the cosine of an angle in a right triangle using sohcahtoa.

What are Trigonometric Ratios?

Right triangles have ratios that are used to represent their base angles. Cosine ratios, along with sine and tangent ratios, are ratios of two different sides of a right triangle. Cosine ratios are specifically the ratio of the side adjacent to the represented base angle over the hypotenuse.

How to find the cosine of an angle in a right triangle using sohcahtoa?

Trigonometric Ratios: Cosine

In this video, we're going to learn about the cosine, which is one of the trigonometric ratios. Given an angle A in a right triangle. Then cos A is equal to the length of the leg that is adjacent to this angle A, over the length of the hypotenuse.

A mnemonic that will help you remember this ratio easily: C. A. H. CAH is a mnemonic for cosine, adjacent, and hypotenuse.

Students learn to find the missing side lengths and the missing angle measures in right triangles using cosine.

SOH CAH TOA is used to remember the trigonometry ratios; sine = opposite over hypotenuse, cosine = adjacent over hypotenuse, tangent = opposite over adjacent. This helps you work out unknown side lengths or unknown angles in a right-angled triangle.

This video is a tutorial on how to apply this rule.

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