Answer:
[tex]\Large \boxed{\mathrm{100\pi \ cm^2 }}[/tex]
Step-by-step explanation:
[tex]\displaystyle area \ of \ circle \ = \ \pi (\frac{diameter}{2} )^2[/tex]
[tex]\displaystyle A \ = \ \pi ( \frac{20}{2} )^2[/tex]
[tex]\displaystyle A \ = \ \pi ( 10 )^2[/tex]
[tex]\displaystyle A \ = \ 100\pi[/tex]
