Perimeter

The perimeter is a length around the boundary of a closed two-dimensional region. The perimeter of a circle is called its circumference.

Perimeter is an elementary-school-level concept. It is listed in the California State Standards for Grade 3.

Classroom Articles on Plane Geometry

	Acute Angle	Hypotenuse
	Altitude	Midpoint
	Angle	Obtuse Angle
	Area	Parallel
	Circle	Perpendicular
	Circumference	Pi
	Collinear	Plane Geometry
	Complementary Angles	Point
	Diameter	Radius
	Geometric Construction	Supplementary Angles
	Golden Ratio	Triangle Inequality
	Golden Rectangle

Classroom Articles on Geometry (Up to Elementary-School Level)

	Cone	Pentagon
	Cube	Polygon
	Cylinder	Prism
	Decagon	Pyramid
	Dodecagon	Quadrilateral
	Equilateral Triangle	Rectangle
	Hendecagon	Regular Polygon
	Heptagon	Right Triangle
	Hexagon	Sphere
	Isosceles Triangle	Square
	Nonagon	Surface Area
	Octagon	Triangle
	Parallelogram	Volume