# How do you find #theta#?

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Which trigonometric ratio is used to find the angle #theta# shown in this drawing?

Which trigonometric ratio is used to find the angle

##### 2 Answers

Whichever ratio you are most comfortable with. For example:

#### Explanation:

You can use any of the six standard trigonometric functions to find

Recall that the **sine** of an angle *arcsine* function, which is essentially the opposite of the sine function:

You may also see the arcsine function written as

It is important to understand the relationship between sine and arcsine. Say you have *inverses*. The input of one is the output of the other, and vice versa.

For cosine, you would use the same process. Just remember the **cosine** of an angle is the side adjacent to the angle divided by the hypotenuse of the triangle. In the diagram, the adjacent side is *arccos* function, which has the same relationship to cosine as arcsin has to sine. And again, you may see arccos written as

So if

To answer your question directly, any trig function can be used to find

#### Explanation:

Adding on to Ken's answer, we can also use the **tangent** of the angle.

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