Question

What is the radius and circumference of a circle if the diameter is 5.6cm. Using the value 22/7.

Answer 1

Given:

The Diameter of a circle = 5.6 cm.

$\setlength{\unitlength}{1cm}\thicklines\begin{picture}(10,6)\put(1,2.2){\line(2,0){1.4}}\put(1.7,2.2){\circle{2}} \put(2.5,2){ Diameter =5.6cm }\end{picture}$

To be found:

The Radius of the circle

And the circumference of the circle.

The Formula for finding the radius of the circle

$\boxed{\rm{\pink Radius = \dfrac{Diameter}{2}}}$

The Formula for finding the circumference of the circle

$\huge{\boxed{\red{\sf Circumference = 2\pi r}}}$

[In which 'r' is the 'radius' of the circle]

Now,

Radius = diameter ÷ 2

            = 5.6 ÷ 2

            = 2.8 cm

$\boxed{\red{\sf Circumference = 2\pi r}}$

$\bf = 2 \times \dfrac{22}{7} \times 2.8\\ \\ \\ \bf = \not2^1 \times \dfrac{22}{7} \times \dfrac{28}{\not{10}^5} \\ \\ \\ \bf = \dfrac{22}{\not7^1} \times \dfrac{\not28^4}{5}\\ \\ \\ \bf = 22 \times \dfrac{4}{5} = \dfrac{88}{5} \\ \\ \\ \bf = 17.6 cm$

Hence,

Radius = 2.8 cm

And

Circumference = 17.6 cm

Answer 2

─────────────────────

$\large\bf\underline{SolutioN}$

• Radius = $\frac{diameter}{2}$

= 5.6 ÷ 2

 = 2.8 cm

─────────────────────

• $\tt \:{\sf Circumference = 2\pi r} \:$

$\begin{lgathered}\ = 2 \times \dfrac{22}{7} \times 2.8\\ \\ = \cancel2^1 \times \dfrac{22}{7} \times \dfrac{28}{\cancel{10}^5} \\ \\ = \dfrac{22}{\cancel7^1} \times \dfrac{\cancel28^4}{5}\\ \\ = 22 \times \dfrac{4}{5} = \dfrac{88}{5} \\ \\ \bf\boxed{= 17.6 cm}\end{lgathered} \:$

─────────────────────

★ So , Radius = 2.8 cm & Circumference = 17.6 cm

─────────────────────