Unformatted text preview: 1.2 Points, Lines, & Planes 1.2
p. 10 What is a definition? What
• Known words used to describe a new Known word word Undefined terms – not formally defined There are 3 in geometry. Point Line Plane Point Point
1. Has no dimension (no length, width, 1. thickness) thickness) 2. Usually represented by a dot 3. Named using one capital letter •B Line Line
1. Extends forever in one dimension (length) 2. Has an arrowhead on each end Has representing the fact that it goes on forever forever 3. Consists of an infinite amount of points 4. Always straight 5. Named with a lowercase script letter or by Named Can be called: 2 points on the line points
l A B Line l Line Line AB or AB Line BA or BA Plane Plane
1. Extends forever in 2 dimensions (length & Extends width) width) 2. A flat surface consisting of infinitely many flat points points 3. Usually represented by a 4sided figure 4. Named with a capital script letter or 3 Named points on the surface of the plane points
A B C W Can be named: Plane W Plane Plane ABC, plane BCA, plane Plane CBA, etc. CBA, More Definitions More
• Collinear points – points that lie on the same line • Coplanar points – Coplanar points that lie on the same plane points Turn to page 10 in your book; look at Turn example #1. example Line Segment (or segment) Line
• A section of a line that has 2 endpoints A B • Named by its endpoints. AB or BA Ray Ray
• Piece of a line with only one endpoint Piece (initial point) and continues forever in the other direction other
B A • Named by the endpoint and a second Named point named on the ray. (name MUST begin with the endpoint!) begin AB Opposite Rays Opposite
• 2 rays that share a common initial point rays and face opposite directions. P Q S • QP and QS are opposite rays. Example: 6 volunteers please! Example
• • • • • • Draw & label points A & B. Draw & label points C & D. Draw AB. Draw BC. Draw AC. Draw DA. • Intersect – 2 or more figures intersect if they have one or more points in common. have • Intersection – all points or sets of points the figures have in common figures • What is the intersection of: AB & DA BC & AC BC & BC More Definitions More When 2 planes intersect, their intersection is a line. their Assignment Assignment ...
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 Spring '08
 GERMAN
 Geometry, Vector Space, Euclidean geometry, Ray Ray, plane plane

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