Point
an exact location in space
Line
a straight path that goes on forever in both directions
Line Segment
a piece of a line that has a beginning point and an endpoint
Ray
a line with ONE endpoint and continues on forever on one direction
Plane
a flat surface that goes on forever in all directions
Angle
2 rays with a common endpoint (vertex)
Vertex
the point where lines, rays, or edges intersect
Acute Angle
an angle that is more than 0 degrees and less than 90 degrees
Obtuse Angle
an angle that is more than 90 degees and less than 180 degrees
Right Angle
an angle that is exactly 90 degrees
Straight Angle
an angle that is 180 degrees, makes a straight line
Complementary Angles
2 angles that add up to 90 degrees
Supplementary Angles
2 angles that add up to 180 degrees
Congruent
same size and same shape
Parallel Lines
coplanar lines that do not intersect (don't get closer or farther apart)
Perpendicular Lines
coplanar lines that cross and form four 90 degree angles
Skew Lines
non-coplanar lines that do not intersect
Vertical Angles
two angles whose sides form two pairs of opposite rays
Adjacent angles
angles having a common boundary or edge (share a common ray)
Linear pair
two angles with one common side (ray), that add up to 180 degrees
Intersecting Lines
Two lines that two lines that cross one another at one common point, but do not form a 90 degree angle.
Midpoint
the point that divides (or bisects) a segment into two congruent segments
Oblique Lines
two lines that intersect and are not perpendicular
Horizontal Line
A line that runs from left to right with a slope of zero
Vertical Line
A line that runs up and down with an undefined slope