Term Definition
Base of a parallelogram This can be any one side.
Altitude Segment that is perpendicular to the base.
Height Length of the altitude.
Base of a triangle This can be any one side.
Height of a trapezoid Perpendicular distance between bases.
Radius of a regular polygon Distance from the center to a vertex.
Apothem Perpendicular distance from center to a side.
Semicircle Half Circle
Minor arc Smaller than a half circle.
Major arc Larger than a half circle.
Arc length Fraction of the circumference.