# Geometry_Definitions_3-D_figures.txt

The flashcards below were created by user ghstechnology on FreezingBlue Flashcards.

1. sphere
set of points in space a fixed distance (radius) from a certain point (center)
2. great circle
points of intersection b/w a plane & the center circle of a sphere
3. small circle
any circle on a plan that is not a great circle
4. conic solid
given a region (base) & a point (vertex) not in the plane of the region, a conic solid is the set of points b/w the vertex & all points of the base, tog. w/ the vertex & base
5. cone
surface of a conic solid whose base is a circle
6. pyramid
surface of a conic solid whose base is a polygon
7. height (altitude) of a pyramid/cone
distance from the vertex to the nearest point of the base on that surface
8. Slant height of a pyramid is...(finish sen.; NOT def)
always shorter than the edge of the lateral surface
9. Slant height of a lateral surface of a pyramid/cone
distance from the vertex to the nearest point of the base on that surface
10. Definition of a plane section of a 3-D figure
intersection of that figure w/ a plane
11. elevation
a view of the front, side, or back of a 3-D figure such as a house or building
12. plan
a bird's eye view of a 3-D figure
13. net
2-D figure that can be folded into a 3-D figure
14. Point-Line-Plane Postulate (7 parts)
• given a line in a plane, there exists a point in the plane not in the line. Given a plane in space there exists a point in space not on the plane
• every line is a set of points that can be put into a one-to-one correspondence w/ the real #s, w/ any point on it corresponding to 0 & any other point corresponding to 1
• through any two points, there is exactly one line
• if two points lie in a plane, the line b/w them lies in the plane
• on a number line, there is a unique distance b/w two points
• through 3 non-collinear points (points that are not on the same line), there is exactly one plane.
• if 2 different planes have a point in common, then their intersection is a line
15. a line is perpendicular to a plane when... (2)
• a line (L) is perpendicular to a plane (X) if and only if it is perpendicular to every line in X through their intersection OR
• if the measureof an angle b/w a line and a plane is 90 degrees it is perpendicular to the plane
16. Can a line which is not in a plane be perpendicular to a line in the plane? Explain.
Yes. Every line oblique to a plane forms a right angle w/ exactly one line in the plane.
17. How many possible intersection points are there of two non-parallel planes? Explain.
Undefined or indeterminable, the answer is a number that cannot be measured.
 Author: ghstechnology ID: 82461 Card Set: Geometry_Definitions_3-D_figures.txt Updated: 2011-04-28 12:32:31 Tags: geometry Folders: Description: geometry Show Answers: