Question Number 20194 by ajfour last updated on 23/Aug/17
$${A}\:{plane}\:{is}\:{drawn}\:{through}\:{the}\: \\ $$$${midpoint}\:{of}\:{a}\:{diagonal}\:{of}\:{a}\:{cube} \\ $$$${perpendicular}\:{to}\:{the}\:{diagonal}. \\ $$$${Determine}\:{the}\:{area}\:{of}\:{the}\:{figure} \\ $$$${resulting}\:{from}\:{the}\:{section}\:{of}\:{the} \\ $$$${cube}\:{cut}\:{by}\:{this}\:{plane}\:{if}\:{the}\:{edge} \\ $$$${of}\:{the}\:{cube}\:{is}\:{equal}\:{to}\:\boldsymbol{{a}}. \\ $$
Commented by ajfour last updated on 24/Aug/17
$${thank}\:{you}\:{Sir}. \\ $$
Commented by mrW1 last updated on 24/Aug/17
$$\mathrm{the}\:\mathrm{section}\:\mathrm{is}\:\mathrm{a}\:\mathrm{regular}\:\mathrm{hexagon}\:\mathrm{with} \\ $$$$\mathrm{side}\:\mathrm{length}\:\mathrm{b}=\sqrt{\mathrm{2}}\left(\mathrm{a}/\mathrm{2}\right)=\mathrm{a}/\sqrt{\mathrm{2}} \\ $$$$\mathrm{A}_{\mathrm{S}} =\frac{\mathrm{3}\sqrt{\mathrm{3}}}{\mathrm{2}}\mathrm{b}^{\mathrm{2}} =\frac{\mathrm{3}\sqrt{\mathrm{3}}}{\mathrm{2}}×\frac{\mathrm{a}^{\mathrm{2}} }{\mathrm{2}}=\frac{\mathrm{3}\sqrt{\mathrm{3}}}{\mathrm{4}}\mathrm{a}^{\mathrm{2}} \\ $$
Commented by mrW1 last updated on 24/Aug/17
Commented by Einstein Newton last updated on 24/Aug/17
$$\mathrm{Does}\:\mathrm{it}\:\mathrm{available}\:\mathrm{on}\:\mathrm{internet}? \\ $$
Commented by ajfour last updated on 24/Aug/17
$${i}\:{dont}\:{know},\:{but}\:{less}\:{chance}. \\ $$