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What’s the equator? Geography and the Earth

By |2018-04-12T08:53:24+00:00August 20th, 2017|Physics|

This globe shows the equator running around the widest part of the Earth. The equator is an imaginary line running around the widest part of the Earth, halfway between the North Pole and the South Pole. So if you are north of the Equator, you're in the Northern Hemisphere. And if you're south of [...]

What is pi? Simple geometry – Math, circles, circumference, diameter

By |2018-04-23T16:01:03+00:00July 29th, 2017|Math|

What is pi? The geometry of a circle What is pi? Pi is a number that is just a little bigger than 3.14. It is the number you get if you divide the circumference of any circle by its diameter. It's the same for all circles. You can approximate pi for yourself by taking some circular things like the tops [...]

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 [...]