Question

The diameter of a circle is 21 cm.
a) Find the length of its radius
b) Find its circumference​

Answer 1

Step-by-step explanation:

as d=2r

= r = d/2

= r = 21/2

r = 10.5cm

circumference of circle = 2πr

= 2×22/7×10.5

= 66cm

Answer 2

Answer:

r

$radius = \frac{21}{2} \\ = 10.5cm \\ circumference = 2 \times \frac{22}{7} \times 10.5 \\ = 2 \times 33 \\ = 66cm$