advertisement

Ruler Postulate 1-5: The points of a line can be put into a one-to-one correspondence with the real numbers so that the distance between any two points is the absolute value of the difference of the corresponding numbers. Practice Find QS (“the length of segment QS”) if the coordinate (“location”) of Q is –3 and the coordinate of S is 21. 3 21 24 24 Definition Congruent: Two segments with the same length. () http://hotmath.com/hotmath_help/topics/congruent-segments/congruent-segments.gif Practice Find which two of the segments XY, ZY, and ZW are congruent. XY = | –5 – (–1)| = | –4| = 4 ZY = | 2 – (–1)| = |3| = 3 ZW = | 2 – 6| = |–4| = 4 Because XY = ZW, XY ZW. Segment Addition Postulate 1-6: If three points A, B, and C are collinear and B is between A and C, then AB + BC = AC. C B A Practice If AB = 25, find the value of x. Then find AN and NB. AN + NB = AB (2x – 6) + (x + 7) = 25 3x + 1 = 25 3x = 24 x=8 AN = 2x – 6 = 2(8) – 6 = 10 NB = x + 7 = (8) + 7 = 15 Practice If DT = 60, find the value of x. Then find DS and ST. 2x - 8 D 3x - 12 S T Definition Midpoint: a point that divides the segment into two congruent segments Segment Bisector: a line, segment, ray, or plane that intersects a segment at its midpoint Practice M is the midpoint of RT. Find RM, MT, and RT. RM = MT 5x + 9 = 8x – 36 +36 +36 5x + 45 = 8x -5x -5x 45 = 3x 15 = x RM = 5x + 9 = 5(15) + 9 = 84 MT = 8x – 36 = 8(15) – 36 = 84 RT = RM + MT = 168 Homework Measuring Segments in Student Practice Packet (Page 5, #1-12)