Mathematics

Inscribed Perimeters

If a quadrilateral has 1 vertex on each side of a square of side 1, its smallest possible perimeter is 2sqrt2.

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Symmetrical Sets

A set of 3 real numbers satisfies the symmetry that any number added to the product of the other 2 will result in 2.  There are 2 such sets: all 1s and all -2s.

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Distances to Vertices

In the square below, points that are closer to the center than one of the vertices is coloured yellow.  The area of the yellow region is 1/2 of the area of the square.

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Number Line Mirrors

Starting with some points on a number line, if we put a mirror somewhere on the number line, it will reflect all existing points in itself so that the resulting set of points are symmetrical around it.

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Area-Bisecting Lines

Every line going through the center of a square bisects its area. Does every line going through the center of an equilateral triangle bisect its area too?

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Chord-bisecting Chords

A circle of radius 5 has chord AB with length 6.  A second chord is drawn here and is bisected by AB.

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Friendly Factor Pairs

The number 6 has two pairs of factors: 2x3 and 1x6.  These two pairs of factors are called friendly because the sum of one pair is equal to the difference of the other pair, ie. 2+3 = 6-1 = 5.

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Sierpinski Pyramid

Let’s remove the central portion of a regular tetrahedron such that what remains are 4 tetrahedrons each with half of the side length of the original.

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