A quadrilateral is a four-sided shape. It could be a square, rectangle, kite, rhombus, parallelogram or trapezium. For any quadrilateral, the angles of the four corners add up to \(360^\circ\).

That cheered him up instantly. Sometime later, after considering his position, Mr Square realised that his new shape was permanent. So he renamed himself Mr Rhombus (after the town Rhom and the ...