Question Number 41787 by Tawa1 last updated on 12/Aug/18
Answered by tanmay.chaudhury50@gmail.com last updated on 12/Aug/18
$${grey}\:{area}={ya}\:+\frac{\mathrm{1}}{\mathrm{2}}\left({x}−{y}\right){a} \\ $$$$=\frac{\mathrm{2}{ya}+{xa}−{ya}}{\mathrm{2}} \\ $$$$=\frac{\mathrm{1}}{\mathrm{2}}\left({x}+{y}\right){a} \\ $$