Question

Find the radius of a circle whose circumference is equal to the sum of the circumference of two circles of radii 15 cm and 18 cm .132974

Answer 1

Let the radius be r cm.
The radius of circle A, r_A= 15 cm
The radius of circle A, r_B = 18
Circumference of circle = circumference of circle A + circumference of circle B
$$\begin{gathered} \Rightarrow 2\mathrm{\pi r}=2{\mathrm{\pi r}}_{\mathrm{A}}+2{\mathrm{\pi r}}_{\mathrm{B}} \\ \Rightarrow \mathrm{r}={\mathrm{r}}_{\mathrm{A}}+{\mathrm{r}}_{\mathrm{B}} \\ \Rightarrow \mathrm{r}=15+18=33\mathrm{cm} \end{gathered}$$