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

Answer:

Given

Radius = 4.2 cm

To find

Circumference = ?

Area of circle = ?

Solution

Circumference of circle = 2πr

\begin{lgathered}= 2 \times \frac{22}{7} \times 4.2 \\ = 2 \times 22 \times 0.6 \\ = 44 \times 0.6 \\ = \textbf{26.4 \: cm}\end{lgathered}=2×722×4.2=2×22×0.6=44×0.6=26.4  cm

Hence , the circumference of the circle is 26.4 cm.

Area of circle =

\begin{lgathered}= \pi {r}^{2} \\ = \frac{22}{7} \times {4.2}^{2} \\ = \frac{22}{7} \times 4.2 \times 4.2\end{lgathered}=πr2=722×4.22=722×4.2×4.2

\begin{lgathered}= {22}{} \times 4.2 \times 0.6 \\ = 22 \times 2.52 \\ = 55.44 \: cm {}^{2}\end{lgathered}=22×4.2×0.6=22×2.52=55.44cm2

Hence, area of circle is 55.44 sq. cm.

Hence,

Final answer..

Circumference of circle is 26.4 cm

Circumference of circle is 26.4 cmArea of circle is 55.44 sq cm.