Ch. 7 - Geometry Flashcards
Geometry
The study of points, lines, angles, surfaces and solids
Line Segment
Part of a line
Ray
A line that has a beginning point but no end
Angle
Two rays with the same endpoint
Vertex
The point where two rays meet
Plane
A flat surface that extends forever in all directions
Parallel Lines
Lines that are always the same distance apart
Intersecting Lines
Lines that cross in the same plane
Perpendicular Lines
Intersecting lines that cross and form four right (90*) angles
Circle
A plane figure whose points are equally distant from the center
Degree
A measure of angles
Acute Angle
Less than a right angle (between 0* and 90*)
Right Angle
Formed by two perpendicular rays (90*)
Obtuse Angle
Larger than a right angle but smaller than a straight angle (between 90* and 180*)
Straight Angle
Two rays form a straight line (180*)
Reflex Angle
Larger than a straight angle (between 180* and 360*)
Protractor
A tool used to draw or measure angles
Polygon
A closed plane figure with three or more sides
Polygon Names
3 sides - Triangle
4 sides - Quadrilateral
5 sides - Pentagon
6 sides - Hexagon
7 sides - Heptagon
8 sides - Octagon
9 sides - Nonagon
10 sides - Decagon
12 sides - Dodecagon
Triangle
A polygon with three sides
Right Triangle
One angle is 90*
Obtuse Triangle
One angle is more than 90*
Acute Triangle
All angles are less than 90*
Scalene Triangle
No sides are equal
