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Warm Up
Making RectanglesDraw and Label a rectangle that has the same area as the one
below and a greater perimeter. Show the Math to prove that it
does.
3 units
4 units
What is Geometry??
http://www.brainpop.com/math/geometryandmeasurement/geometry/
Point: It has location and nothing else. No size. No height. No depth. No friends.
Line: A straight, unbroken set of points that goes on forever. It has infinite length but no thickness.
A
B
AB BA
A
Plane: A surface with length and width but no thickness.
Vocabulary #1
Talk to your neighbor and come up with five examples from your life of points, lines, and planes.
AB BA
Line Segment: A line that has two endpoints.
AB
Ray: A line with ONE endpoint.
YB
A AB AY
Vocabulary #2
Coplanar: On the same plane
Collinear: On the same lineF Z P
Look at this Picture and tell me which tennis balls are coplanar, and which sets of 3 are collinear
AB BA
Line Segment: A line that has two endpoints.
AB
Ray: A line with ONE endpoint.
YB
A AB AY
More Vocabulary
Postulate: (or axiom) is a statement that is accepted without proof.
Postulates
1-1-1 Through any two points there is exactly one line.
1-1-2 Through any three noncollinear points there is exactly one plane containing them.
1-1-3 If two points lie in a plane, then the line containing those points lies in the plane.
More Postulates
1-1-4 If two lines intersect, then they intersect in exactly one point.1-1-5 If two planes intersect, then they intersect in exactly one line.
Classwork
1. Explain why any two points are collinear.
2. Which postulate explains the fact that two straight roads cannot cross each other more than once?
3. Explain why points and lines may be coplanar even when the plane containing them is not drawn.
4. Name all the possible lines, segments, and rays for the points A and B. Then give the maximum number of planes that can be determined by these points.
5. GET ORGANIZED Draw a graphic organizer In each box, name,describe, and illustrate one of the undefined terms.
Homework:
P. 9 #1-12P. 10 #30, 35, 36, 38
