point
an exact location in space
line
straight path of points that goes on forever in two directions
line segment
a part of a line with two endpoints
ray
a part of a line with one endpoint and extends forever in one direction
parallel lines
lines that never cross and stay the same distance apart
intersecting lines
lines that pass through the same point
perpendicular lines
intersecting lines that form square corners
angle
formed by two rays that have the same endpoint
vertex
a common endpoint
acute angle
a measure between 0 and 90 degrees
right angle
angle with a measure of 90 degrees
obtuse angle
a measure between 90 and 180 degrees
straight angle
a measure of 180 degrees
circle
a closed plane figure made up of all the points the same distance from the center
radius
any line segment that connects the center to a point on the circle
diameter
any line segment through the center that connects two points on the circle
chord
any line segment that connects two points on the circle (not through the center)
central angle
an angle whose vertex is the center of a circle