## The pre-calculus unit circle

In pre-calculus, the unit circle is sort of like unit streets, it’s the very small circle on a graph that encompasses the 0,0 coordinates. It has a radius of 1, hence the unit. The figure here shows all the measurements of the unit circle:

## Right triangles and trig functions for pre-calculus

If you’re studying pre-calculus, you’re going to encounter triangles, and certainly the Pythagorean theorem. The theorem and how it applies to special right triangles are set out here:

## How to format interval notation in pre-calculus

In pre-calculus you deal with inequalities and you use interval notation to express the solution set to an inequality. The following formulas show how to format solution sets in interval notation.

## Absolute value formulas for pre-calculus

Even though you’re involved with pre-calculus, you remember your old love, algebra, and that fact that absolute values then usually had two possible solutions. Now that you’re with pre-calculus, you realize that absolute values are a little trickier when you through inequalities into the mix. Never fear, the following formulas show you how to deal with absolute values in pre-calculus.

## Trig identities for pre-calculus

Of course you use trigonometry, commonly called trig, in pre-calculus. And you use trig identities as constants throughout an equation to help you solve problems. The always-true, never-changing trig identities are grouped by subject in the following lists: