1. Using Coordinate Geometry Skills to Prove
Assertions
We will use our formulas for:
slope
midpoint
distance between two points
distance between a point and a line
To prove assertions about triangles, quadrilaterals and
circles
Some other concepts you might use are:
Parallel lines have equal slopes
Perpendicular lines have reciprocal slopes
If something forms a right angle then c2 = a2 + b2
If lines are horizontal then the slope is zero.
Parallelograms have opposite sides that are parallel and equal in length
You must also keep in mind the properties of the shape you are dealing
with. For example a square has 4 equal sides, a rhombus has
perpendicular bisectors....
1

2. Here are some more useful facts about geometric shapes
2

3. To make the correct verifications
1) Make a sketch, this visual will help you when you go to make your
proof. (The sketch is not enough to make a proof though)
2) Decide which properties of the shape you are working with you are
going to use in your proof.
3) Use your formulas along with the known properties of the shape,
and use these to make the correct verifications
Example
3

4. 4

5. 5

6. 6

7. Remember
7

8. 8