Originally, each country had its own, and rather poorly reproducible, unit of luminous intensity; it was necessary to wait until 1909 to see a beginning of unification on the international level, when ... Continue reading
A circle is the round counterpart of a square. To find the area of a square, one multiplies the length by the width. A circle doesn't have these, however, so there has to be a different way to ... Continue reading
What 3 dimensional shape will pass through a rectangle, triangle and circle each time filling the whole space? The answer may surprise you in it's simplicity. Before I tell you what it is, see if you ... Continue reading
A circle is what you get if you take a straight line and bend it around so that its ends touch. You can demonstrate this by taking a piece of stiff wire and doing just that: bring the ends of the wire ... Continue reading
