Prentice Hall Geometry

1. 1-6 The Coordinate Plane part 2 L.E.Q. How do you find the coordinates of the midpoint of a segment in the coordinate plane?

2. Midpoint On a number line formula:

3. On a coordinate plane formula: Where is the x coordinate of the midpoint and is the y coordinate of the midpoint.

4. y 10 10 9 8 7 x = 1 x = 9 6 A(1, 7) y = 7 y = 3 5 y 4 3 B(9, 3) 2 C(5, 5) x 1 x 0 -1 -2 -2 10 -1 2 4 6 8 10 -2 3 7 1 9 -2 5 0 Midpoints Find the midpoint, C(x, y), of a segment on the coordinate plane.

5. QS has endpoints Q(3, 5) and S(7, -9). Find the coordinates of its midpoint M. EXAMPLE: Finding the midpoint.

6. Use the example to model your solution for this problem. ON YOUR OWN:

7. y 10 10 9 Finding an Endpoint 8 Suppose C(3, 5) is the midpoint of AB. Find the coordinate of B. 7 B(-1, 8) 6 5 4 3 A(7, 2) 2 C(3, 5) 1 x 0 -1 -2 -2 10 -1 2 4 6 8 10 -2 3 7 1 9 -2 5 0 x-coordinate of B y-coordinate of B Replace x1with 7and y1with 2 B(x, y) is somewhere over there. midpoint Multiply each side by 2 Add or subtract toisolate the variable

8. EXAMPLE: Finding an Endpoint. The midpoint of AB is M(3, 4). One endpoint is A(-3, -2). Find the coordinates of the other endpoint B.

9. The midpoint of DG is M(-1, 5). One endpoint is D(1, 4). Find the coordinates of the other endpoint G. ON YOUR OWN:

10. Hw: pg. 46-47 #s 18-30 even, 44, 46.Chapter 1 Review:Pgs 61-63 #s 1 - 48 all.