[RESOLVED] Circular segment height?

[Justa Lol]

So i have an assignment at school. the first part of the assignment is finding out how many litres of liquid are in a cylinder. I have the following variables:

d = 50 cm (diameter of circle)
L = 120 cm (length of cylinder)
h = 10 cm (height of circular segment)

The Figure to the left is sideview of the cylinder, and the figure to the right is front view.


first part is easy.
Find out how much liquid is in the cylinder

A=r^2/2 * ((pi*v)/180 - sin(v))
A=312,5*(1,854587-0,96)=279,5581 cm^2

V_(cylinder) = 279,5581 cm^2 * 120 cm = 33546,97 cm^3
V_(cylinder) = (33546,97 cm^3)/(1000 cm^3/L) = 33,54697 L

now the second part is where i'm stuck at.
i need to find the new height of the circular segment, if i add 50 L liquid. so our new V_(cylinder) is 50 + 33,54697 = 83,54697 L.

how would i go about doing this? i can't exactly isolate V from the previous formula?