Area of triangle = \( \frac{1}{2} \times \text{base} \times \text{height} \)<br><br>
&bull; Square side = 20 cm, so area of square = 20 × 20 = 400 cm&sup2;<br>
&bull; The shaded triangle covers half the square<br>
&bull; Area = \( \frac{1}{2} \times 400 = 200 \) cm&sup2;<br><br>
Final Answer: 200