Question

Given that diameter of a circle is $d$ and radius of the circle is $r$. Find circumference of the circle.

• A. $\pi \times d$
• B. $2\pi \times r$
• C. $2\pi \times d$
• D. $\pi \times r$

Answer 1

Answer: (A), (B)

$2\pi \times r$

Let's draw a circle with diameter AB having length $d$ and radius having length $r$.


As we know,
Circumference of a circle $=\pi \times \text{dimeter}$
Hence, Circumference of the circle $=\pi \times d$
Option (a) is correct.

$\to$ Diameter is twice the radius of a circle.
Hence, $d=2r$
Circumference of the circle $=\pi \times d=\pi \times 2r=2\pi r$
Option (b) is correct.