<PRE><B>Question 326279</B>
The needed formula to find the altitude is

A = (L)^2 + L(sqrt[(L)^2 + (2h)^2]

A = surface area

L = length of one side of the base

h = height or altitude

240 = (12)^2 + 12(sqrt[(12)^2 + (2h^2)]

Can you take it from here and solve for h?

http://en.wikipedia.org/wiki/Square_pyramid</PRE>