Question Number 97033 by joki last updated on 06/Jun/20
Answered by mr W last updated on 06/Jun/20
Commented by mr W last updated on 06/Jun/20
$${green}\:{line}=\sqrt{{r}^{\mathrm{2}} −\left(\frac{{a}}{\mathrm{2}}\right)^{\mathrm{2}} }={a}−{r} \\ $$$$−\left(\frac{{a}}{\mathrm{2}}\right)^{\mathrm{2}} ={a}^{\mathrm{2}} −\mathrm{2}{ar} \\ $$$$\Rightarrow{r}=\frac{\mathrm{5}}{\mathrm{8}}{a}=\frac{\mathrm{5}×\mathrm{10}}{\mathrm{8}}=\frac{\mathrm{25}}{\mathrm{4}}=\mathrm{6}.\mathrm{25} \\ $$
Commented by joki last updated on 06/Jun/20
$${thank}\:{you}\:{sir} \\ $$