Khan Academy
Introduction to the Unit Circle, Trigonometry
In this video, Sal shows how the sine and cosine of an angle are defined on the unit circle. He inscribes a 30-60-90 triangle in the unit circle and explains how to use SOH-CAH-TOA to find the circle's coordinates.
Curated OER
Intro to the Trigonometric Ratios
This video introduces the basics of trigonometry. It starts by defining a right triangle and showing two different examples of finding the ratios of sine, cosine, and tangent using the SOH-CAH-TOA mnemonic. This resource could be used as...
Curated OER
How Do You Find a Missing Side of a Right Triangle Using Cosine?
Trigonometry? What's trigonometry. Well, something to do with triangles, right? Right! Right triangles! In this problem, find the missing length of one of the sides. So set this up as a ratio: cosine(A) = adjacent side length divided by...
Curated OER
Sin Cos Tan - Basic Trigonometry
Trigonometry learners can get confused about the relationships in a right triangle. This video clearly lays out how to solve for the length of one side of a triangle using cosine. Though not engaging, it is educational. Have your...
Curated OER
How Do You Find the Cosine of an Angle in a Right Triangle?
What's a trigonometric ratio? It is a ratio between two sides of a right triangle. In this problem, find cosine(A) in the given right triangle. Use the ratio of the adjacent side divided by the hypotenuse to find cos(A). The instructor...
Curated OER
Adjacent Right Triangle Problems
The instructor identifies the terms used to solve for the angle of adjacent right triangles. He does not have an example to solve a problem.