acute angle

An angle measuring less than 90º.

angleA figure formed by the joining of two rays with a common endpoint.
lineA line is a one-dimensional figure, which extends without end in two directions.
line segmentA finite section of a line between any two points that lie on the line.
obtuse angle

An angle measuring more than 90º and less than 180º.

planeIn geometry, a two-dimensional surface that continues infinitely. Any three individual points that don't lie on the same line will lie on exactly one plane.
pointA zero-dimensional object that defines a specific location on a plane. It is represented by a small dot.
rayA half-line that begins at one point and goes on forever in one direction.
right angle

An angle measuring exactly 90º.

straight angle

An angle measuring exactly 180º.

vertexA turning point in a graph. Also the endpoint of the two rays that form an angle.
vertexA turning point in a graph. Also the endpoint of the two rays that form an angle.