Circles
Circle
A round plane figure whose boundary consists of points equidistant from a fixed point.
Center
The center of the circle is the fixed point from which all points on the boundary of the circle are equidistant.
Radius
The distance from the center of a circle to the outside. The radius of the circle is half the diameter of the circle. The plural of radius is radii.
a parallelogram with 4 right angles and 4 congruent sides
Diameter
The distance across the circle going through the center. The diameter is twice the radius.
Arc
A part of the circumference.
Area
The space inside a 2D shape.
A parallelogram with 4 congruent sides
Minor sector
A minor sector has a central angle which is less than 180 Degrees
Major arc
A major arc is greater than half the circumference.
Minor arc
A minor arc is less than half the circumference
Rectangle
A parallelogram with 4 right angles
Chord
A line segment going from one point of the circumference to another but does not go through the center.
Sector
A section of the circle created by two radii.
Major sector
A major sector has a central angle which is more than 180 Degree
Parallelogram
quadrilateral with both pairs of opposite sides being parallel
Secant
A line that goes through the circle at two points.
Tangent
A straight line that touches the circle at a single point only.
Quadrant
A quarter of a circle, created by two perpendicular radii
Semi circle
Half of a circle. Could be considered a sector where the circle has been split by the diameter.