Question

If the radius of a circle is 4.2 cm, compute its area and circumference.​

Answer 1

Area of a circle = πr2

So, area = π(4.2)2 = 55.44 cm2

Circumference of a circle = 2πr

So, circumference = 2π(4.2) = 26.4 cm

Answer 2

$\huge\bf\fbox\red{Answer:-}$

Circumference of circle = 2πr

$= 2 \times \frac{22}{7} \times 4.2 \ = 2 \times 22 \times 0.6 \ = 44 \times 0.6 \ = \textbf{26.4 \: cm}$

Hence , the circumference of the circle is 26.4 cm.

Area of circle

$= \pi {r}^{2} \ = \frac{22}{7} \times {4.2}^{2} \ = \frac{22}{7} \times 4.2 \times 4.2$

$= {22}{} \times 4.2 \times 0.6 \ = 22 \times 2.52 \ = 55.44 \: cm {}^{2}$

Hence, area of circle is 55.44 sq. cm.

Final answer,

Circumference of circle is 26.4 cm

Area of circle is 55.44 sq cm.