20 08, 2017

## What’s the equator? Geography and the Earth

This globe shows the equator running around the widest part of the Earth. Where is the equator? The equator is an imaginary line running around the widest part of the Earth, [...]

29 07, 2017

## Area of a sphere – Volume of a sphere

This is a sphere. A sphere is a three-dimensional circle. Or you could say that a sphere is the set of all the points that are at the same distance from the center [...]

29 07, 2017

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 [...]

29 07, 2017

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

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 [...]

29 07, 2017

## What is a cylinder? Simple geometry

This is a cylinder. What can you find around your house that's a cylinder? A cylinder is a circle moved through space to make a solid form. The ends are circles that [...]

28 07, 2017

## Circumference of a circle – Geometry

The geometry of a circle, with circumference labelled What is the circumference? The circumference of a circle is the distance all the way around the circle. It's the same as the perimeter, but [...]

28 07, 2017

## Proof for the area of a circle

Proof for the area of a circle: Divide a circle up into sections like an orange Euclid's proof We know it's true that A=πr-squared is the area of a circle, but how can we prove [...]

28 07, 2017

## Definition of a circle – Geometry

A circle is the set of points on a plane that are all the same distance away from a center point. A circle is the set of points on a plane that are all [...]

28 07, 2017