Please look at these notes and copy them into your notebook for credit.
This video walks you through using the distance formula 3 times to classify a type of triangle
Source: http://www.youtube.com/watch?v=BhVtkXePj9k
This video shows examples of classifying triangles and quadrilaterals in the coordinate plane.
Source: http://www.youtube.com/watch?v=4ErQ2tZ2xT4