What is a quadrilateral? Squares and rectangles
This is a quadrilateral. A quadrilateral is a flat shape, in one plane, defined by four points at the four corners. A quadrilateral has four sides. The sides can be of any length. [...]
This is a quadrilateral. A quadrilateral is a flat shape, in one plane, defined by four points at the four corners. A quadrilateral has four sides. The sides can be of any length. [...]
A pyramid with a square base. A pyramid is a three-dimensional solid form made out of triangles. Some pyramids also use a square. There are two common kinds of pyramids: triangular pyramids that you [...]
This is a triangular prism A prism is the solid shape you get if you move a flat polygon through space. A prism has five planes: a top, a bottom, and [...]
What is a point? A circle is the set of points in a plane that are all the same distance away from a center point. What is a point? A [...]
A plane goes on infinitely in all directions. Just as a line is made of an infinite number of points, a plane is made of an infinite number of lines that are right [...]
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 [...]
Perpendicular lines Two lines are perpendicular if they cross at right angles. You can test this by extending the lines until they cross (if they do not cross then they are parallel). Where the [...]
The perimeter of this rectangle is in dark green. The perimeter of a square or a triangle is the distance all the way around the edge - the green strip in this picture. The circumference of [...]
Two parallel lines Two lines are parallel if they are in the same plane but they can go on forever without ever crossing. You can test this by seeing if you can [...]
A number line is infinite in both directions - definition of a line A line of points A line is made of an infinite number of points that are right next [...]