Question

The difference between the circumference of a circle and the radius of the circle is 111 cm . The radius is :

• A. 23 cm
• B. 20 cm
• C. 21 cm
• D. None of these

Answer 1

The correct option is C 21 cm

Given
Circumference of a circle with radius $\left(r\right)$-radius $\left(r\right)=111$ cm
$(2\pi r-r)=111$
$r(2\pi -1)=111$
$r(\frac{44}{7}-1)=111$
$r\left(\frac{44-7}{7}\right)=111$
$\therefore r=111\times \frac{7}{37}=3\times 7=21cm$
$\therefore$ radius is 21 cm.