Shoutbox

Not sure if this is the right place but if anyone can help it would be really great.

A rain gutter is to be constructed from a long metal sheet of width 36cm. The gutter is 20m long and is constructed by bending up the edges of the sheet through an angle x to form a symmetrical shape with a cross section.
(1)The dimensions of the cross-section of the gutter are in the ratio 1:1:1
(2)The dimensions of the cross-section of the gutter are auch that the base is 16cm
All I know is that I have to use calculus to solve and that integration is not necessary

Please help me!