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What is a radius? Radius of a circle

By |2018-05-10T10:38:52+00:00July 29th, 2017|Math|

What is a radius? The geometry of a circle What is a radius? The radius of a circle is the distance from the center point to the edge of the circle. It's the same distance anywhere on the circle, because the circle has radial symmetry. So it doesn't matter where you measure the radius on the circle, [...]

Diameter of a circle – Geometry

By |2017-07-29T09:34:48+00:00July 29th, 2017|Math|

The geometry of a circle The diameter of a circle is the distance across the circle at the widest part of the circle. The diameter is always equal to twice the radius of the circle, because the radius starts from the center of the circle and goes straight to the edge. Learn by doing: measure the diameter [...]

Circumference of a circle – Geometry

By |2017-07-28T08:49:28+00:00July 28th, 2017|Math|

The geometry of a circle The circumference of a circle is the distance all the way around the circle. It's the same as the perimeter, but a special word that we only use for the perimeter of a circle. The circumference is always equal to twice the radius of the circle times π (pi), or 2πr. Dinner [...]

Area of a circle – Geometry

By |2017-07-28T00:00:26+00:00July 28th, 2017|Math|

The geometry of a circle The area of a circle is the flat surface inside its circumference. The area is always equal to the radius squared, multiplied by π (pi). Here's a proof that this is always true for any circle. Learn by doing: figure out the area of some circles around you. Radius Diameter Circumference of [...]