Drawing Exercises

Question for geometry homework?

In exercises 1-3, Let A,B,C and D be four points in a plane. Tell whether the given condition is sufficient to conclude that AB+BC+CD=AD. Justify your answer by using the Segment Addition Postulate or by sketching a counterexample. 1.) B is between A and C and B is between A and D 2.) B is between A and D and C is between B and D. 3.) B and C are both between A and D Can someone please explain this to me? You don't have to solve it, just explain how to do it because I don't really understand the question... Thanks!

Public Comments

1. You have a line with four points on it marked A to D. The ENDS of the line are A and D. That is the total length of the plane you need to consider. If Segment AB is 2.0 inches and BC is 5.0 inches and CD is 4.0 inches then AD is 2.0+5.0+4.0 for a total of 11.0 inches. Draw it out on your paper.
2. Yes. According to the Segment Addition Postulate, you can add up the distances between the points to equal the total distance between two further points: 2 10 20 a--b----------c--------------------d ab+bc+cd=ad ad=32 hyphens ab=2 hyphens bc=10 hyphens cd=20 hyphens *now plug in the variables* 2+10+20=32 12+20=32 32=32 That is correct. The length of AD is the same as ab+bc+cd b/c of this postulate. I can't really explain it from here. That postulate is as basic as it gets. Hope this helps.