Question Number 167252 by mkam last updated on 10/Mar/22
Answered by mr W last updated on 11/Mar/22
$$\frac{\partial{f}}{\partial{t}}=−\mathrm{2}{x}×{r}\:\mathrm{sin}\:{t}+\mathrm{2}{x}×{r}\:\mathrm{cos}\:{t}−\mathrm{2}{y}\:{r}\:\mathrm{sin}\:{t}+\mathrm{2}{y}×{r}\:\mathrm{cos}\:{t} \\ $$$$\frac{\partial{f}}{\partial{r}}=\mathrm{2}{x}×\mathrm{cos}\:{t}+\mathrm{2}{x}×\mathrm{sin}\:{t}+\mathrm{2}{y}\:\mathrm{cos}\:{t}+\mathrm{2}{y}×\mathrm{sin}\:{t} \\ $$