1. GEOMETRY Section 4.7 Intro to Coordinate Proofs

2. Formula Reminders Distance = Midpoint = Slope = Used to
Find lengths of segments
Show that two segments are congruent
Midpoint =
Find the midpoint of segments
Used to show that segments are bisected
Slope =
Show that two lines are parallel
Show that two lines are perpendicular

3. Convenient Position for Figures
Use the origin as a vertex, keeping the figure in Quadrant I.
Center the figure at the origin.
Center a side of the figure at the origin.
Use one or both axes as sides of the figure.

4. Examples Conveniently position the following objects
Square with sides b) Isosceles triangle
of 6 units with base 10 &
height 7.

5. Coordinate Proofs
1) Graph the figure (If no points given, graph conveniently
Use distance, midpoint, or slope formulas to show what is needed.
Justify each step with formula name or reason from the green sheet.

6. Example: Use the square in the example above to prove that the diagonals bisect each other.

7. Example: Show that the rectangle below has diagonals of the same length.

8. Assignment #7: page 270 #’s 2-4,8,9,30,(38)