## What is a prism? Rectangular and triangular prisms

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 [...]

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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 [...]

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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 [...]

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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 [...]

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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 [...]

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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 [...]

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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 [...]

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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 [...]

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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 [...]

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This is an isosceles triangle. Definition of an isosceles triangle Isosceles triangles have at least two sides that are exactly the same length. This forces two of their angles to also be acute angles of exactly [...]

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This is a hexagon. See, it has six sides that are all the same length. Definition of a hexagon A hexagon is a flat shape, all in one plane, with six [...]