Law of Cosine and Heron's Formula

Law of Cosines are used to solve oblique triangles when you are given either three sides of the triangle (SSS), or if you are given two sides and their included angle (SAS).



This equation is best used when you are given all three sides of the triangle:

                                               

This equation is best used when you are given two sides and their included angle:

                                             




Heron's Area Formula is used to find the area of an oblique triangle:

                                             


What is "s"? s is equal to the semi-perimeter, which is half of the triangles perimeter.