Question

If the diameter of a circle is 42cm. Find area & circumference of circle & radius.​

Answer 1

Given :-

Diameter of Circle = 42 cm.

To Find :-

Circumference of Circle :-

Radius of Circle :-

Formula Used Here :-

Circumference of Circle = 2πr

Solution Start :-

2 × Radius = Diameter

2 × Radius = 42

Radius = 42 ÷ 2

$\large \fbox \green{Radius = 21 cm}$

$Circumference \: of \: Circle \: = >2πr \\ \\ Circumference \: of \: Circle \: = > 2 \times \frac{22}{7} \times 21 \\ \\ Circumference \: of \: Circle \: = > 2 \times \frac{22}{\cancel {7}} \times \cancel {21} \\ \\ Circumference \: of \: Circle \: = > 2 \times22 \times 3 \\ \\ Circumference \: of \: Circle \: = > 132 \: cm$

$\large \fbox \red{Circumference~of~Circle~=~132~cm}$

Answer 2

Answer:

Area =1386$cm^{2}$ ,circumference =132$cm^{2}$, Radius = 21cm

Step-by-step explanation:

According to the information provided in the question it is given as

Diameter of circle =42 cm

We need to find the circumference  of circle and radius

First understand the meaning of circumference and radius

The circumference of a circle is the length of the boundary of the circle The distance between the center and any point on the circumference is known as the radius of the circle. The radius is a constant value.

Radius of circle = D / 2

                        r= 42 /2

                       r =21cm

Hence by using the value of r we get the value of circumference

by applying the formula of circumference

$C =2\pi r\\C= 2\times \frac{22}{7}\times 21$

Converting into lowest term we get the answer

$C = 2\times 22\times 3$

(As both 7 and 21 are  divisible by 7)

$C=132cm^{2}$

Area of circle =

$A = \pi r^{2} \\A= \frac{22}{7}\times 21^{2}$

$A=\frac{22}{7}\times 21\times 21\\A =22\times3\times 21$

(As 7 and 21 both are divisible by 7)

$A=1386cm^{2}$

Hence  area of circle is 1386$cm^{2}$ and circumference  is 132$cm^{2}$ and radious is 21cm