Geometry 1 Flashcards
Line segment (and notation)
All the points between two points (including the endpoints). The two points with a line above it.
Ray (and notation)
A line that has a start point but does not end. Notation is the starting point, the other point that sets the direction, with an arrow above both letters.
Line (and notation)
A line that goes off in both directions. Notation is like ray but has a double arrow.
Colinear
Points that sit on the same line.
How many dimensions does a point have?
Zero.
Planes (and notation)
A flat, 2-d surface that extends infinitely far. Specified by three, non-colinear points.
Coplanar
Points that lie in the same plane.
Angle
A shape, formed by two lines or rays diverging from a common point (the vertex).
Acute angle
Angle that is smaller than 90
Obtuse angle
Angle that is larger than 90
Complementary angles
Two angles that sum to 90
Supplementary angles
Two angles that sum to 180 (straight angle)
Alternate interior / exterior angles
Formally, alternate interior / exterior angles are two interior / exterior angles which lie on different parallel lines and on opposite sides of a transversal. If the lines are parallel, the angles are equal.
Corresponding angles
Corresponding angles are created where a transversal crosses other (usually parallel) lines. The corresponding angles are the ones at the same location at each intersection.
Vertical angles
Each of the pairs of opposite angles made by two intersecting lines. Are always equal.
