1. Lesson 1.5: Measuring Segments Lesson 1.6a: Measuring Angles

2. Absolute Value
A number’s distance from zero. REMEMBER: DISTANCE IS ALWAYS POSITIVE!

3. Postulate 1-5
The Ruler Postulate: The distance between points on a number line (or on a ruler) is the absolute value of their difference.
Remember: Distance is always positive!
Note: The distance between A and B, or the length of , is written as AB (no line above the letters!)
Ex: 1. Find DE
2. Find CE
3. Find AC

4. Congruence If AB = BC, then
Congruent Segments: Segments that have the same length
If AB = BC, then
Ex: Are and congruent?
(Check if AB = BC)
Do you see any other pairs of congruent segments?

5. Postulate 1-6 A
Segment Addition Postulate: If 3 points A, B, and C are collinear and B is between A and C, then AB + BC = AC B C
Example: If TV = 46, find the value of x. Then find the values of TU and UV. T U V
3x - 2
4x + 6

6. Postulate 1-6 A
Segment Addition Postulate: If 3 points A, B, and C are collinear and B is between A and C, then AB + BC = AC B C
Example: Q is the midpoint of Find PQ, QR, and PR. P Q R
2x + 14
5x + 2

7. Angles Angle: An angle is formed by two rays with the same endpoint. BK 1
Name:
Name: J C R P 2 3

8. Types of Angles Acute Angle: less than 90° Right Angle: Exactly 90°
Straight Angle: exactly 180°
Obtuse Angle: more than 90° 8

9. Postulate 1-7
Protractor Postulate: O is a point with opposite rays called and going to the left and right. Any ray drawn up from O creates and angle with a measure between
and
Let’s talk about measuring angles with a protractor…

10. 180

11. Postulate 1 - 8 Angle Addition Postulate: Angle Addition Postulate:
Ex:
Ex.

12. Lesson 1.5: Measuring Segments Lesson 1.6a: Measuring Angles
HW: p.33 #6-14 even, 20-23, 35-37
p.40 #1-8, 13-14
THT: Can do #1-7, 9-10, 13-16
Terms: acute angle, obtuse angle, right angle, straight angle, congruence