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Bellwork. 4) Suppose you know PQ and QR. Can you use the segment addition postulate to find PR? Explain. 1-3 Measuring Segments and Angles. Postulate 1 : Ruler post. The points on a line can be matched with those on the real # line.
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Bellwork 4) Suppose you know PQ and QR. Can you use the segment addition postulate to find PR? Explain.
Postulate 1: Ruler post. • The points on a line can be matched with those on the real # line. • The real # that corresponds to a point is the coordinate of the point. • If you find the difference between the coordinates of 2 points, then take the absolute value, you will have the distance between the points.
Ruler post. (continued) • The length of AB can be found by x2-x1 • **The symbol for the length of AB is AB. A B x1 x2
Example: Find AB. A B Point A is at 1.5 and B is at 5. So, AB = 5 - 1.5 = 3.5
Is Alex between Ty and Josh? Yes! In order for a point to be between 2 others, all 3 points MUST BE collinear!! Ty Alex Josh No, but why not? How about now?
Post. 1-6: Segment Addition Post. • If B is between A & C, then AB + BC = AC. • If AB + BC = AC, then B is between A & C. C B A
EX. • If EG= 59, what are EF and FG? 8x-14 F G 4x+1 E
OYO. • If EG= 120, what are EF and FG? 4x+6 F G 7x+15 E
Ex: if DE=2, EF=5, and DE=FG, find FG, DF, DG, & EG. D E F G FG=2 DF=7 DG=9 EG=7
Congruent ( ) Segments • Segments that have the same length. If AB & XY have the same length, Then AB=XY, but AB XY Symbol for congruent
Midpoint- a point that divides the segment into two congruent segments • Segment Bisector- a point, line, or ray that intersects a segment at its midpoint
Ex.. • Q is the midpoint of PR. What are PQ,QR, and PR? 6x-7 5x +1 Q R P