The formula of the volume of a cylinder:
[tex]V=\pi r^2H\\\\where:\\\\r-a\ radius\\H-a\ height\\\pi r^2-an\ area\ of\ base[/tex]
We have:
[tex]V=900\ liters\\1L=1dm^3\ therefore\ V=900L=900dm^3[/tex]
and
[tex]H=20\ dm[/tex]
substitute:
[tex]\pi r^2\cdot20=900\ \ \ |:20\\\\\pi r^2=45\ dm^2[/tex]
Answer: The area of a base of the cylinder is equal 45 dm².
