Hey everyone. Just needing some help on a question about volumes involving a triacontakaihenagon. This is a shape with 31 sides, according to Google.

"The base of the tower is in the shape of a regular triacontakaihenagon, with each side measuring one metre on the exterior, and the tower rises vertically to a height of 31 metres, and it has a flat roof. The walls and roof are 30 centimetres thick."

How many litres of water are required to fill the entire tower?

I suppose you have to find the radius to be able to work out the area to work out the volume? But having trouble with the radius...

Can anyone help? Thanks in advance