Q$.3.$ A tent on a square base of side $2$a consists of four vertical sides of height $b$ surmounted by a regular grid of height $h.$ If the volume enclosed is $V,$ show that the area of the canvas in the tent is $\frac{2V}{a}-\frac{8h}{3}+4a\sqrt[\phantom{2}]{h^2+a^2}.$ Show that the least area of the canvas corresponding to a given volume $V.$ if a and $h$ can both vary, will be given by: $a=\frac{\sqrt[\phantom{2}]{5h}}{2}$ and $h=2b$