## Cosine Law

The Cosine law is used when we have a side-side-side (SSSTriangle 1.) or when we have a side-angle-side (SAS Triangle 2.). We us the the angle formula with CosC= in the SSS triangle to find the missing angles, while Csquared= formula is used to find a missing side in the SAS triangle. The angle and the side with the same variable will always be opposite of each other

## Lets do an SAS example!

In the SAS we have an angle between 2 sides. We want to find the third side so we would use formula #2 (above).

1.Plug in the appropriate measures

2. Solve for x using the calculator

3. Square root this number

4. Don't forget your units

1.Plug in the appropriate measures

2. Solve for x using the calculator

3. Square root this number

4. Don't forget your units

## Lets do an SSS example!

In this triangle we have 3 given sides and we want to find angle C. We will use formula 1 for this problem. We will need to use the inverse of Cos to solve.

1.Plug in the appropriate measures

2. Solve for Cos(C using a calculator

3. Use the inverse of Cos to get your final answer

4. Don't forget your units

1.Plug in the appropriate measures

2. Solve for Cos(C using a calculator

3. Use the inverse of Cos to get your final answer

4. Don't forget your units