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 \(altitude\)

\( base~x ~altitude = right ~section~x~lateral~edge\)

\(altitude = \frac{A_{right ~section}~x~lateral~edge}{A_{base}}\)

\(altitude = \frac{1.29 (2.31)}{1.41}\)

\(altitude = 2.11 ~ft\)