1. Postulate: A rule that is accepted without proof (also called an axiom). The first point A A x1x1 The second point B B x2x2 How do you find the distance between the two points?

2. Ruler Postulate: The distance between two points is the difference between the coordinate points The first point A A x1x1 The second point B B x2x2 AB = I x 1 – x 2 I

3. Segment Addition Postulate: BAC AB BC AC If B is between A and C, then AB + BC = AC. If AB + BC = AC, then B is between A and C

4. What if… PSQR PS = 20 PQ = 8 And QR = RS Find QR PS = PQ + QR + RS PS - PQ = QR + RS 20 - 8 = 2QR 12 = 2QR 6 = QR

5. Pairs Check – Segment Addition Postulate M is between L and N. Find lengths of each LM = 3x + 8 MN = 2x – 5 LN = 23

6. Find the distance from A to C X 5 6 What can we use to find the distance? (2, -1) (-4, 4)

7. Distance Formula-Similar to Pythagorean Theorem EXAMPLE: Find the distance between (-2, 5) and (4, -1) Point 1: (-2, 5)Point 2: (4, -1) 4-25 Distance

8. Distance Formula YOU TRY: Find the Distance between (3, 7) and (-1, -5) Point 1: (3, 7)Point 2: (-1, -5) 3-57 Distance

9. Homework Book page 21 Problems (20-42 even)