The diameter of a circle is 28 cm. Find its :

(i) circumference

(ii) area

Given:

Diameter = d = 28 cm

Radius = r = $\dfrac{d}{2}$ = $\dfrac{28}{2}$ = 14 cm

(i) Circumference of a circle = 2πr

$= 2 \times \dfrac{22}{7} \times 14\\[1em] = \dfrac{44}{7} \times 14 \\[1em] = \dfrac{616}{7}\\[1em] = 88 \text{ cm}$

Hence, the circumference of a circle is 88 cm.

(ii) Area of a circle = πr²

$= \dfrac{22}{7} \times 14^2\\[1em] = \dfrac{22}{7} \times 196\\[1em] = \dfrac{4,312}{7}\\[1em] = 616 \text{ cm}^2$

Hence, the area of a circle is 616 cm².