$($Problem $4-20$ Points$)$ Show through a function that we can get an approximation of the volume of water in the tank if we know the length of the tank, the radius and the level of the water in the tank.$($Hint: Show how to formulate the function below.$)$

$V(r,h,L)=L*[arccos(\frac{r-h}{r})r^2-(r-h)\sqrt[\phantom{2}]{2rh-h^2}]$