Question Number 208021 by efronzo1 last updated on 02/Jun/24
Answered by A5T last updated on 02/Jun/24
$$\frac{{CD}}{{CD}+{r}}=\frac{{r}}{{r}+{AB}}\Rightarrow\frac{{r}+{AB}}{{r}+{CD}}=\frac{{r}}{{CD}} \\ $$$$\frac{{r}+{AB}}{\mathrm{8}+{r}}=\frac{{r}+{CD}}{\mathrm{3}+{r}}\Rightarrow\frac{{r}+{AB}}{{r}+{CD}}=\frac{\mathrm{8}+{r}}{\mathrm{3}+{r}}=\frac{{r}}{{CD}} \\ $$$$\Rightarrow{CD}=\frac{{r}\left(\mathrm{3}+{r}\right)}{\mathrm{8}+{r}} \\ $$$$\frac{{AB}}{{AB}+{r}}=\frac{{r}}{{CD}+{r}}={AB}\left({CD}+{r}\right)={r}\left({AB}\right)+{r}^{\mathrm{2}} \\ $$$${AB}=\frac{{r}^{\mathrm{2}} }{{CD}}=\frac{{r}\left(\mathrm{8}+{r}\right)}{\mathrm{3}+{r}} \\ $$$$\left({r}+{AB}\right)^{\mathrm{2}} +\left({r}+{CD}\right)^{\mathrm{2}} =\left(\mathrm{11}+\mathrm{2}{r}\right)^{\mathrm{2}} \\ $$$$\Rightarrow\left({r}+{AB}\right)^{\mathrm{2}} =\left(\mathrm{11}+\mathrm{2}{r}\right)^{\mathrm{2}} −{r}^{\mathrm{2}} \left(\mathrm{1}+\frac{\mathrm{3}+{r}}{\mathrm{8}+{r}}\right)^{\mathrm{2}} \\ $$$${AB}=\sqrt{\left(\mathrm{11}+\mathrm{2}{r}\right)^{\mathrm{2}} −{r}^{\mathrm{2}} \left(\mathrm{1}+\frac{\mathrm{3}+{r}}{\mathrm{8}+{r}}\right)^{\mathrm{2}} }−{r}=\frac{{r}\left(\mathrm{8}+{r}\right)}{\mathrm{3}+{r}} \\ $$$$\Rightarrow{r}=\mathrm{12}\Rightarrow{Diameter}=\mathrm{24} \\ $$
Answered by A5T last updated on 02/Jun/24
$${AB}=\sqrt{\mathrm{8}\left(\mathrm{8}+\mathrm{2}{r}\right)}=\frac{{r}\left(\mathrm{8}+{r}\right)}{\mathrm{3}+{r}}\Rightarrow{r}=\mathrm{12} \\ $$
Answered by A5T last updated on 02/Jun/24
$$\frac{{r}}{{r}+{AB}}=\frac{\mathrm{3}+{r}}{\mathrm{11}+\mathrm{2}{r}}\Rightarrow\mathrm{11}{r}+\mathrm{2}{r}^{\mathrm{2}} ={r}\left(\mathrm{3}+{r}\right)+\mathrm{3}{AB}+{rAB} \\ $$$${AB}=\frac{{r}\left(\mathrm{8}+{r}\right)}{\mathrm{3}+{r}} \\ $$$$\left(\mathrm{8}+{r}\right)^{\mathrm{2}} ={r}^{\mathrm{2}} +\frac{{r}^{\mathrm{2}} \left(\mathrm{8}+{r}\right)^{\mathrm{2}} }{\left(\mathrm{3}+{r}\right)^{\mathrm{2}} }\Rightarrow{r}=\mathrm{12} \\ $$
Answered by efronzo1 last updated on 02/Jun/24