Finding Cosine of an Angle

Related Topics:
More Lessons for Trigonometry
Math Worksheets

Share this page to Google Classroom

Examples, solutions, videos, worksheets, 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.

Trigonometry SOH CAH TOA (trigonometric ratios)
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.

Trigonometric Ratios: Cosine
How to find the cosine of an angle in a right triangle using sohcahtoa?
Using the CAH Formula
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.

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

Try the free Mathway calculator and problem solver below to practice various math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.
Mathway Calculator Widget

We welcome your feedback, comments and questions about this site or page. Please submit your feedback or enquiries via our Feedback page.