Geometry Glossary

acute angle:	An angle with a measure less than 90.
acute triangle:	A triangle with three acute angles.
adjacent angles:	Two coplanar angles with one common side and a common vertex, but no common interior points.
adjacent sides of a polygon:	Sides which intersect at a vertex.
alternate interior/exterior angles:	Interior/ Exterior, nonadjacent angles which he on opposite sides of a transversal.
altitude of a prism:	Any segment perpendicular to the planes containing the two bases with endpoints in these planes.
altitude of a triangle:	A segment from a vertex of the triangle perpendicular to the opposite side.
altitude of a trapezoid:	A perpendicular segment from any point on one base to the other base.
angle:	Two rays with a common endpoint. The rays are the sides, the endpoint is the vertex.
angle bisector:	A segment, line, ray, or plane which divides an angle into two con- gruent angles.
apothem of a regular polygon:	The length of a perpendicular segment from the center of the polygon to a side.
arc:	An unbroken part of a circle measured by referring to an angle whose vertex is the center of the circle.
area of a circle:	The limit of the areas of inscribed regular polygons as the number of sides increases indefinitely.
area of a polygon:	The number of square units in the region bounded.

Note: The terms in this collection may not be entirely accurate.
They are for reference only.

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