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More Lessons for Trigonometry

Math Worksheets

The following diagram shows how the unit circle is related to sin, cos and tan. Scroll down the page for more examples and solutions on the unit circle, sine, cosine, and tangent.

In some other lessons, we have covered the three common trigonometry functions sine, cosine and tangent using the basic SOH-CAH-TOA definition.### Sine Function

### Cosine Function

### Tangent Function

More Lessons for Trigonometry

Math Worksheets

The following diagram shows how the unit circle is related to sin, cos and tan. Scroll down the page for more examples and solutions on the unit circle, sine, cosine, and tangent.

In some other lessons, we have covered the three common trigonometry functions sine, cosine and tangent using the basic SOH-CAH-TOA definition.

In this lesson, we will extend the definition of the trigonometry functions by using the unit circle.

A **unit circle** is a circle of radius one unit with its center at the origin.

As illustrated in the following diagram:

For a point (*x*, *y*) on the unit circle; sin θ = ⇒ sin θ =* y *

As illustrated in the following diagram:

For a point (*x*, *y*) on the unit circle; cos θ = ⇒ cos θ =* x*

As illustrated in the following diagram:

For a point (*x*, *y*) on the unit circle; tan θ =

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