Area of a Triangle, Given 3 Sides, Heron's Formula

explains universe🌐 on Instagram: "This timeless geometry illusion uses wooden spheres stacked like billiard balls to trick the eye. A triangle made of 15 balls arranged in five rows has one ball removed, leaving 14. When these are repositioned, they appear to form a perfect four-row triangle, yet four balls are somehow left over. It feels like a ball vanished—but nothing actually disappears. The secret lies in spacing and packing. The larger triangle has tiny gaps created by hand placement, whi