নিচের চিত্রে কয়টি ত্রিভুজ আছে?

The diagonals and the centre line make 5 small triangles (top, left, bottom and two on the right). Joining the two right-hand pieces gives 1 more, and each half of the rectangle cut by a diagonal gives 4 more (2 per diagonal). Total = 5 + 1 + 4 = 10.