1. Objectives: Define length & congruence Identify and use the segment addition postulate Warm-Up: Place 10 dishes along the 4 edges of a table so that each edge had the same amount of dishes.

2. Vocabulary: Number Line: A line whose points correspond with the set of real numbers. 0 123 45-2 -3-4 -5

3. Vocabulary: Coordinate of a Point: The real number represented by a point on the number line. 0 123 45-2 -3-4 -5 A Note: 2 is the coordinate of point A

4. Vocabulary: Length of AB: The measure of AB is |a-b| or |b-a|. 0 123 45-2 -3-4 -5 BA AB = | a – b | = | -3 – 2| = | -5 | = 5 AB = | b – a | = | 2 – -3| = | 2 + 3 | = | 5 | = 5 or

5. Vocabulary: Congruence: The relationship between figures have the same shape and same size. (congruent segments are segments that match exactly) ~ =

6. Vocabulary: Segment Congruence Postulate: If two segments have the same length then they are congruent. Also, if two segments are congruent they have the same length.

7. Vocabulary: Segment Addition Postulate: If point R is between points P and Q on a line, then PR + RQ = PQ P R Q PR PQ RQ

8. Example 1: Find the measures (lengths) of AB, AX, & XB. AB = 0 123 45-2 -3-4 -5 B A X AX = XB = (The measure of AB is |a-b| or |b-a|.)

9. Collins Writing Type 1: The length of a segment must be a positive number. Explain why the order of the coordinates does not matter when calculating length. 3 lines ~ 2 minutes _________________________________________

10. Example 2: Name all of the congruent segments in each figure. AB, DC, EF, & HG and AD, BC, EH, & FG E F HG A B C D

11. Example 3: Point B is between points Q and R on QR. Sketch a figure for each set of values, and find the missing lengths. QB = 20; BR = 10; QR = ______. QB = 50; BR = ____; QR = 110. QB = ____ ; BR = 17; QR = 52. Q Q Q B B B R R R

12. Example 4: Find the indicated value. AC = 60; x= _____. AC = 36; x = ____. A A B B C C 4x 11x x 17

13. AB = 15; AC= _____. AC = 36; AB = ____. A BC 4x+3 2x A BC 3x+6 x+2

14. Homework: Page 22 Numbers 11-25