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Geometry. Agenda: ENTRANCE Review Practice 1-3 QUIZ Foldable Sec. 1.4 – Measuring Segments and Angles Practice Assignment Exit Measurement Activity. 1-4 Measuring Segments and Angles. Congruent segments. Two segments with the same length. AB = 2.5 cm CD = 2.5 cm.
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Geometry • Agenda: • ENTRANCE • Review Practice 1-3 • QUIZ • Foldable • Sec. 1.4 – Measuring Segments and Angles • Practice Assignment • Exit • Measurement Activity
Congruent segments • Two segments with the same length AB = 2.5 cm CD = 2.5 cm
Midpoint of a segment • A point that divides a segment into two congruent segments. Point Y is the midpoint of
Bisect • To cut into two equal or congruent parts Point Y bisects Line n bisects
Angle • Formed by two rays with the same endpoint An angle can be named in four ways
Classifying Angles • Acute—less than 90º • Right—equal to 90º • Obtuse—greater than 90º but less than 180º • Straight—equal to 180º
Congruent angles • Two angles with the same measurement
Postulate 1-5 Ruler Postulate • The points of a line can be put into 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. AB = | -4 – 2 | = | -6 | = 6
Postulate 1-6 Segment Addition Postulate • If three points A, B, and C are collinear and B is between A and C, then AB + BC = AC AB + BC = AC 2 + 7 = 9
Postulate 1-8 Angle Addition Postulate • If point B is in the interior of ADC, then mADB + mBDC = mADC. • If ADC is a straight angle, then mADB + mBDC = 180º. mADB + mBDC = mADC mADB + mBDC = 180º 142 + 38 = 180 84 + 39 = 123
Example #1 • If AB = 25, find the value of x. Then find AN and NB.
Example #2 • Point M is the midpoint of . Find RM, MT, and RT.
Example #3 • Name the angle in four ways.
Example #4 • Suppose that m1 = 42º and mABC = 88º. Find m2.
Example #5 • If mDEG = 145º, find mGEF.
Assignment/Practice • Practice 1-4 • 1-3, 5, 6, 8, 12-17, 21 • Measurement Activity