Lesson 1-3 Section 1-5

Definition

 To find the Midpoint of a number line, we simply take the average of the distance.  Say that we are trying to find the distance between two points, a and b. To take the average of these points we add a and b together and then divide it by 2. I.E. a+b/2

Questions  Example 1 will be done on the board.  We can also use the fact that the midpoint is in the middle and therefore cuts the segment in half. Let’s see what theorem 1-1 says about that.

Theorem 1-1 Midpoint Theorem  If M is the midpoint of AB, then AM ~= MB

Example 2

Example 3

Question  We saw what a midpoint looks like on a line, but what if we are trying to find the midpoint in a coordinate plane?  The coordinate plane has points (x,y). To find the middle of a segment we simply find the average of the distance between the endpoints. Let’s see how that is done…..

Definition

Example 4

Example 9

Example 10

Example 11

Practice  Try the following problems:  Pg. 40 # 7-13 odd