Coordinate Geometry is geometry that uses the coordinate plane for analyzing shapes, distances, and transformations. The distance formula is used to find the distance between two points on the coordinate plane and is derived from the Pythagorean Theorem. The midpoint formula is used to find the point that is halfway between two points. Polygons graphed in the coordinate plane can be transformed and/or resized to other positions through rotations, reflections, translations, and dilations.
Pythagorean Theorem--An Informal Proof (01:03) Finding the Hypotenuse--D.C. Walking Distance (02:44) Find the Base--A Sail (02:41)
The Distance Formula & the Midpoint Formula (06:05) 
Properties of Linear Graphs (07:19)