http://dark.z5lcip4dafatwwa6hvyibizpzwycvwp67cjga3hzjhxhwvuyaqavxnid.onion/math/526
One can also view this from the purview a prospective square in an equilateral triangle. Start by drawing the top side of the square, then the two legs of the square. The top must be the same length as half the sides of the overall triangle, yet the legs must be shorter than this per the right-angled triangle principles.