Geometry
Circles
A circle is the set of points equidistant from a center point. It is defined by its radius or diameter.
Key Formulas
Area
Pi times radius squared.
Circumference
Pi times diameter.
Key Concepts
Radius and diameterArc lengthSector areaTangent lines
Worked Examples
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Angles
An angle is formed by two rays sharing a common endpoint. Angles are measured in degrees or radians.
Triangles
A triangle is a polygon with three sides. The angles sum to 180°.
Area
Area measures the amount of space inside a two-dimensional shape.
Volume
Volume measures the amount of space inside a three-dimensional object.