# Trigonometry

## Law of Cosines: How to Use & Practice Examples

We have already seen how to solve triangles using the Law of Sines. Such problems involve two sides and two angles. The Law of Cosines (or the Cosine Rule) is used when we have all three sides involved and only one angle. The formula is:   c is the unknown side a and b are the given sides γ is ...

## Law of Sines: How to Use & Practice Examples

The Law of Sines (or the Sine Rule) tells us that the ratio of a side length to the sine of its opposite angle is the same for all three sides. As a formula, it looks like this: or   In the formula, a is the side and α is its opposite angle, b is the side and β is ...

## SOHCAHTOA

SohCahToa is an acronym which helps you remember how to find the basic trig functions: sine, cosine and tangent. Use SohCahToa with a right triangle only! To check if your triangle is the right triangle, look for the 90-degree angle. It’s the largest one in the triangle and it usually has a small square which indicates the right angle. (You ...

## Unit Circle: How to Memorize & Use

What is the Unit Circle? The unit circle is a circle, centered at the origin, with a radius of 1. This circle helps us find the exact values of some trigonometric functions and not the decimal approximations the calculator will give us. For example, it’ll help us find the exact value of sin or cos30°. You don’t have to memorize ...