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Acute Angle

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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