Question

The sum of a radii of two circle is $140cm$ and the difference of their circumference is $88cm$. Find the diameter of the circles

Answer 1

Let the radius of first circle be $x$

The radius of second circle is $140-x$

The circumference of first circle be $2\pi x$

The circumference of second circle is $2\pi (140-x)=280\pi -2\pi x$

The difference is $88cm$

$⟹280\pi x-2\pi x-2\pi x=884\pi (70-x)=8870-x=\frac{88\times 7}{88}x=63cm$

The radius second circle is $77cm$

The dimateres are $126cm,154cm$