we know that
the surface area of the top of the water
is calculated with the formula of the area of a circle
[tex] A=\pi r^{2} [/tex]
Step 1
Find the radius of the water tank in the middle of the tank
by proportion
[tex] \frac{10}{3} =\frac{5}{x} \\ \\ 10*x=5*3\\ \\ x=\frac{15}{10} \\ \\ x=1.5m [/tex]
so
For h=5 m
the radius is equal to r=1.5 m
Step 2
Find the surface area
[tex] A=\pi*1.5^{2} [/tex]
[tex] A=7.07\ m^{2} [/tex]
therefore
the answer is
the surface area of the top of the water is [tex] 7.07\ m^{2} [/tex]
