Volume of a prism can be calculated in two ways
\(V = A_{base}~x ~altitude\)
\(V = A_{right ~section}~x~lateral~edge\)
Equate both equations and isolate \(altitude\)
\( base~x ~altitude = right ~section~x~lateral~edge\)
\(altitude = \frac{A_{right ~section}~x~lateral~edge}{A_{base}}\)
\(altitude = \frac{1.29 (2.31)}{1.41}\)
\(altitude = 2.11 ~ft\)