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# Video:How to Apply Ratios in Math

Ratios are an important part of math that help you relate quantities. Learn about ratios and how to apply them in math in this how-to video from About.com.See Transcript

## Transcript:How to Apply Ratios in Math

Hi, my name is Bassem Saad. I'm a Math Ph.D. candidate at U.C. Davis, and I'm here today for About.com to show you how to apply ratios to mathematics.

### How to Use Ratios in Math

Remember, a ratio is a mathematical way of relating two quantities, and typically comes up in Geometry and Trigonometry. For example, the sine of an angle on a right triangle is just the ratio of the adjacent side to the hypotenuse.

Ratios are also used to convert units. For example, there are about 3.3 feet in every meter.

### Ratios in a Word Problem

Let's take a look at this word problem. Say we need to cut a beam of wood down to about two meters in length, but we only have an Imperial Standard measuring tape. Determine how many feet are in two meters. Here we have the ratio of one meter to every 3.3 feet, but we want to know how many feet are in two meters.

So we can write out the proportion of two meters to x feet. These are only equal if we multiply both sides of the ratio by two. So, two times 3.3 is 6.6. That means x has to equal 6.6 feet. From that example it's clear that carpenters must be able to apply ratios on a regular basis. In fact, any professional who has to depend on measurements must be able to apply ratios in mathematics.