Chapter 6.2 Law of Cosines

The law of cosines allows to solve for the values of the side lengths and angle measures. The law of cosines can be written in many ways, but the most common is:

also can be written as:

This just shows that you can use the law of cosine to solve for
all side lengths and can be written for all sides.

There is also an alternative writing where its solved in terms for the angle measures:

Also in this lesson we learned a very convenient method for solving the area of all kinds of Triangles.

Its called Heron's Area Formula :

but it's very important to remember what s is equal to.
s=(a+b+c)/2