Question Number 55300 by Tawa1 last updated on 20/Feb/19
Answered by tanmay.chaudhury50@gmail.com last updated on 21/Feb/19
$${p}=\mathrm{2}\left(\mathrm{2}{x}+{x}\right) \\ $$$$\frac{{dp}}{{dt}}=\mathrm{6}\frac{{dx}}{{dt}} \\ $$$${A}=\mathrm{2}{x}×{x}=\mathrm{2}{x}^{\mathrm{2}} \\ $$$$\frac{{dA}}{{dt}}=\mathrm{4}{x}×\frac{{dx}}{{dt}} \\ $$$$\mathrm{18}=\mathrm{4}×\mathrm{1}×\frac{{dx}}{{dt}}\:\left[\mathrm{2}{x}=\mathrm{2}\:{length}\:{given}\right] \\ $$$$\frac{{dx}}{{dt}}=\frac{\mathrm{9}}{\mathrm{2}} \\ $$$${so}\:\frac{{dp}}{{dt}}=\mathrm{6}×\frac{\mathrm{9}}{\mathrm{2}}=\mathrm{27}{m}/{sec} \\ $$
Commented by Tawa1 last updated on 21/Feb/19
$$\mathrm{God}\:\mathrm{bless}\:\mathrm{you}\:\mathrm{sir} \\ $$