Step-by-step explanation:
Area of a circle is pi times r-square
[tex]\pi \: {r}^{2} [/tex]
So...
[tex] \frac{22}{7} \times \frac{21}{2} \times \frac{21}{2} = \frac{22 \times {21}^{2} }{28} [/tex]
Do the rest yourself, my calculator and pen are not handy. Sorry
