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Warm up (TI). True or False. If false explain why. A, E, and C are collinear. A, G, and D are coplanar. G is the intersection of AC and GE. C lies on the intersection of AC and CE. On EF, point F is the initial point. A. F. E. G. D. C. Warm up 2 (TI).
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Warm up (TI) • True or False. If false explain why. • A, E, and C are collinear. • A, G, and D are coplanar. • G is the intersection of AC and GE. • C lies on the intersection of AC and CE. • On EF, point F is the initial point. A F E G D C
Warm up 2 (TI) • Find the coordinates of the points listed below. • Find EF, GH, EG and FH. E F G H
Segments and Their Measures Chapter 1 Section 3
Postulates • A postulate (axiom) is a rule that is accepted to be true without proof. • Ruler postulate Every point on a line can be matched one to one with the real numbers. The real number that corresponds to a point is the coordinate of the point.
Distance on a number line • The distance between point A and B (AB) is the absolute value of the difference between the coordinates of A & B. A B 2 -2 AB =
Number Line • With your partner and complete the activity below. • Using the number line below calculate the following: • PQ, QR, PR, RS, PS, QS P Q R S
Segment Addition Postulate • If B is between A and C, then AB + BC = AC. • If AB + BC = AC, then B is between A and C. A B C
Example • Suppose M is between L and N. Find the length of LM and MN. LM = 3x + 8 MN = 2x – 5 LN = 23
Distance on the Coordinate Plane • The distance formula =
Remembering the distance formula Sung to the tune of "On Top of Old Smokey“… When finding the distanceBetween two points,Subtract the two x'sDo the same for the y's.Now square both these numbers,And find out their sum.When you take the square rootThen you are all done!
Try these… E • Do any of the following segments have the same length? How can you verify your answer? EF, FG, GH F G H
Congruent Segments • Segments that have the same length If AB = CD, then AB = CD. ~ Symbol for congruency ~ If AB = 5 cm and CD = 5 cm then AB = CD.
Congruency • Remember: • Congruency is not the same as Equality. • Congruency has to do with size and shape. • Equality has to do with numbers (length). • One implies the other but they are not the same! • Always use a segment bar when naming segments that are congruent. • Drop the bar when stating they are equal.
Writing Assignment • Write a letter to a fictitious student in our class who was absent today. Explain to them how to find the distance between two points on a number line and on the coordinate plane. Be sure to include examples and step by step instructions
Homework • Complete Assignment #3