# ACT Math : How to find the sine of a missing side

## Example Questions

### Example Question #91 : Trigonometry

In the triangle below,  units and  units. What is ?

Explanation:

Because , we need to first find the length of BC.

Using the Pythagorean theorem,

.

### Example Question #2 : How To Find The Sine Of A Missing Side

What is the value of  in the triangle above? Round to the nearest hundredth.

Explanation:

We know that the sine of an angle is:

Therefore, we can write for this question:

This allows us to solve for  easily:

Rounding, this gives us .

### Example Question #92 : Trigonometry

A right triangle has leg lengths  and . What is the sine of the angle opposite from the side of length ?

Explanation:

Using SOHCAHTOA, the sine of an angle is simply the length of the side opposite to it over the hypotenuse; however, we do not have the length of the hypotenuse yet.

Using the Pythagorean Theorem, we can solve for it:

So, the sine of this angle is: