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Geometry Basics. Sections covered: 1.3 Points, Lines, & Planes 1.4 Segments, Rays, Parallel Lines, & Planes. Space. the set of all points. Points. location in space with no size, represented by a small dot and a letter. Line.
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Geometry Basics Sections covered: 1.3 Points, Lines, & Planes 1.4 Segments, Rays, Parallel Lines, & Planes
Space • the set of all points
Points • location in space with no size, represented by a small dot and a letter
Line • series of points that extends in two opposite directions without end • Named:
Collinear Points • points that lie on the same line
Example 1 • Are points E, F, and C collinear? • Are points E, F, and D collinear?
Plane • flat surface that has no thickness • Think of a sheet of paper
Coplanar • points and lines in the same plane
Example 2 • Each surface of a cube represents part of a plane. Name the plane represented by the front of the cube.
Postulates & Axioms • Accepted statements of facts • We will use these in proofs to formulate ideas
Postulate 1-1 • Through any two points there is exactly one line.
Postulate 1-2 • If two lines intersect, then they intersect in exactly one point.
Postulate 1-3 • If two planes intersect, then they intersect in exactly one line.
Example 3 • What is the intersection of plane HGFE and plane BCGF?
Postulate 1-4 • Through any three noncollinear points there is exactly one plane.
Example 4 • Shade the plane that contains A, B, and C.
Example 4 • Shade the plane that contains E, H, and C.
segment • part of a line consisting of two endpoints and all points between them
ray • part of a line consisting of one endpoint and all the points of the line on one side of the endpoint
opposite rays • two collinear rays with the same endpoint • always form a line!
Example 5 • Name all of the segments and rays in the figure:
parallel lines • coplanar lines that do not intersect
skew lines • noncoplanar (not parallel and do not intersect)
Example 6 • Name all segments parallel to DC. • Name all segments skew to DC.
Parallel Planes • planes that do not intersect • a line and a plane that do not intersect are also parallel
Example 7 • Use the diagram to name: • two pairs of parallel planes • a line that is parallel to plane GHIJ
Homework… • p. 19: 2-8 even, 14, 20, 38, 40, 50, 52, 55-60 • p. 25: 12-23