PORTION comprises of four EQUAL triangles with base and height \[\frac{25}{2}\] CM and \[\frac{18}{2}\] cm = 9 cm Area of shaded portion \[=4\left[ \frac{1}{2}\TIMES base\times height \right]\] \[=4\times \frac{1}{2}\,\times \frac{25}{2}\times 9=22\,sq.\,cm\]