Question

The circumference of a circle of diameter d is

1 point

(a) πd

(b) 2πd

(c) 12 πd

(d) πd2

​

Answer 1

(i) Circumference = 2πr or πd, where d = 2r is the diameter of the circle.

(ii) Area = πr2 or πd2/4

(iii) Area of semi-circle = πr2/2

(iv) Area of a quadrant of a circle = πr2/4

Answer 2

The circumference of a circle of diameter d is πd

Given :

The diameter of a circle is d

To find :

The circumference of the circle is

(a) πd

(b) 2πd

(c) 12 πd

(d) πd²

Formula :

For a circle of radius r unit the circumference of the circle = 2πr unit

Solution :

Step 1 of 2 :

Find radius of the circle

Here it is given that the diameter of a circle is d

The radius of the circle

= r

= d/2

Step 2 of 2 :

Find circumference of the circle

The circumference of the circle

= 2πr

$\displaystyle \sf{ = 2 \times \pi \times \frac{d}{2} }$

= πd

Hence the correct option is (a) πd