Question

If the circumference of a circle is $60$ cm more than its diameter, then the circumference is?

• A. $14\pi$cm
• B. $28\pi$cm
• C. $35\pi$cm
• D. $42\pi$cm

Answer 1

Answer: (B)

$28\pi$cm

Given: Circumference of circle $=60+$ Diameter

$\Rightarrow 2\pi r=60+2r$

$\Rightarrow$ $2\times \frac{22}{7}\times r=60+2r$

$\Rightarrow$ $\frac{22}{7}\times r=30+r$

$\Rightarrow$ $30=\frac{22}{7}r-r$

$\Rightarrow$ $30=\frac{15r}{7}$

$\Rightarrow r=14$

Hence circumference $=2\pi r$

$=2\times \frac{22}{7}\times 14$

$=88$