1. Quick Warm-Up Identify an angle, segment, ray, line, and point in the figure. D 2 E F G H

2. REVIEW How many different angles can be named in the figure? Name them. A C B V

3. Section 1.2 Measuring Length Unit 1

4. The length of a segment AB Coordinate of a Point – A real number – In the figure, -3 is the coordinate of the point A, and 4 is the coordinate of the point B Number Line: – A line that has been set up to correspond with the real numbers.

5. DEFINITION: Length of AB Let A & B be points on a number line, with coordinates a and b. Then the measure of AB, which is called its length, is:

6. Example Find the measures (lengths) of MN, NP, & MP on the number line below. MNP

7. Unit Length The distance from 0 to 1 on a ruler Most common unit lengths are inches and centimeters. 01234

8. Congruent Segments Congruent figures are figures that are the same size & shape. If you move one onto the other, they will match perfectly. Tick marks are used to show which segments are congruent The symbol for congruence is:

9. “XY = YZ” is read as “Segment XY is congruent to Segment YZ”

10. Name all congruent segments

11. If 2 segments have the same length as measured by a fair ruler, then the segments are congruent. ALSO, if 2 segments are congruent, then they have the same length as measured by a fair ruler. SEGMENT CONGRUENCE POSTULATE

12. What does that mean?? If XY = YZ, then ___________________ If XY = YZ, then _____________________

13. SEGMENT ADDITION POSTULATE If point R is between points P and Q on a line, then PR + RQ = PQ. PQ R + =

14. Examples Point A is between points M and B on MB. Sketch each figure & find the missing lengths. – MA = 30 AB = 15 MB = _____ – MA = 15 AB = ____ MB = 100 – MA = ____ AB = 13.3 MB = 29.6

15. EXAMPLES Find the indicated value – PR = 25 x = _____ – PQ = 25 PR = ______ PQR 2x3x PQR 5x3x PQR 2x+1x