Acute Angle

An acute angle is an angle that measures less than 90 degrees.

Acute angle is an elementary-school-level concept. It is listed in the California State Standards for Grade 4.

Prerequisites

Angle:

An angle is a measure of the amount of rotation about the point of intersection of two lines or line segments that is required to bring one into correspondence with the other.

Classroom Articles on Plane Geometry

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

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