Geometry · Lesson 9
Coordinate Geometry
Placing geometric figures on the coordinate plane lets us use algebra to prove geometric facts. The distance formula, midpoint formula, and slope connect algebra and geometry in a powerful way.
Quick Check
1. What is the distance between (1, 2) and (4, 6)?
3
5
7
√7
2. The midpoint of (2, 4) and (8, 10) is:
(6, 6)
(5, 7)
(4, 5)
(10, 14)
3. The slope of the line through (0, 3) and (4, 11) is:
4
2
½
−2
4. Two lines are perpendicular. One has slope 3. The other has slope:
3
−3
−1/3
1/3