Help Needed

im currently making a slider, the problem is i want to know a good width to height ratio, at the moment it will be 180cm across (simply b/coz ive already built this part) now for the height i was thinking maybe 120cm but just looking at that it seems maybe a bit top heavy. So just give me your opinion on that.
and next for all the smart maths people out there can someone please work out the trigonometry stuff (angles to cut the slope) for me for either/both 120cm or 110cm??
surely someone knows how to do the shizzle

Give it to them in feet and inches... not too many understand our cm stuff.

lots of things to consider. Is your slider a floating slider? what type of floatation? How wide is the base? Base width would depend on the flotation device used. Hieght would depend on base width. When you say across do you mean 180cm long or wide?

okay... my conversion is pretty dogde but here goes.
its 21 feet long
6 feet wide
4 feet high.
floating slider using refridgerator foam for the floatation.
will it be to top heavy at 4 feet or should i change it to 3'7"
i think thats pretty much correct

Your flotation base is 6 feet?

180cm/30cm in a foot seems about right to me. why whats wrong with a 6 foot width?

Jeff can you help me any further. does it all seem in proporsion, will it tip over