Question

if the circumference of circle is 440cm find the value of
i. radius of circle​

Answer 1

Given :

• The circumference of circle is 440 cm.

To Find :

• The value of radius of circle.

Calculations :

Conception :

Here, we are given with the circumference of the circle which is 440 cm.

Formula used -

• $\underline{\boxed{ \rm{2\pi \: r }}}$

Where,

• $\underline{\boxed{ \rm{\pi = \dfrac{22}{7} }}}$

Plugging the values,

$: \implies \rm 2\pi \: r$

Inserting the values in the equation,

$: \implies \rm \: 440 = 2 \times \dfrac{22}{7} \times r$

Multiplying the numbers in numerator,

$: \implies \rm \: 440 = \dfrac{22 \times 2}{7} \times r$

By multiplying,

$: \implies \rm \: 440 = \dfrac{44}{7} \times r$

Now, transposing 7 to L.H.S and multiplying it with 440,

$: \implies \rm \: Radius = 440 \times 7 = 44$

On multiplying,

$: \implies \rm \: Radius = 3080 = 44$

Now, dividing 3080 by 44,

$: \implies \rm \: Radius = \cancel\dfrac{3080}{44}$

On cancelling the numbers,

$: \implies \underline{ \boxed{\rm{ Radius = 70 \: cm}}} \blue{ \bigstar}$

Therefore, the radius of circle is 70 cm.

Abbreviations used :-

• L.H.S = Left hand side

Answer 2

❍ Let the radius of circle be x cm respectively.

$\\ \underline{\bigstar\boldsymbol{According\;to\;the\;Question:}}$

• Here,The circumference of circle is 440 cm.So that we can apply the formula of circumference of circle is 2πr.

$\\ \twoheadrightarrow\;\sf{440 = 2\pi r}\\ \\ \twoheadrightarrow\;\sf{440 = 2 \times \frac{22}{7} \times x} \\ \\ \twoheadrightarrow\;\sf{ \frac{440}{2} = \frac{22}{7} \times x} \\ \\ \twoheadrightarrow\;\sf{220 = \frac{22}{7} \times x} \\ \\ \twoheadrightarrow\;\sf{220 \times 7 = 22 \times x} \\ \\ \twoheadrightarrow\;\sf{1540 = 22 \times x} \\ \\ \twoheadrightarrow\;\sf{x = \frac{1540}{22}} \\ \\ \twoheadrightarrow\; \boxed{\frak{x = 70}} \red{\bigstar}$

• Hence,The radius of circle is 70 cm.