Question

find the area of the circle given that
a. radius=20cm
b. diameter=42cm​

Answer 1

Given = a. r = 20cm

b. diameter = 42cm

Find = area of circle

Solution ⤵

Area of circle if

A. Radius = 20 cm

$are a \: of \: circle = \pi \: r {}^{2} \\ = 22 \div 7 \times 20 \times 20 \\ = 22 \times 400 \div 7 \\ = 8800 \div 7 \\ = 1257.14286cm {}^{2}$

Area of circle when r = 20 cm = 1257.14 cm

$1257.14cm {}^{2}$

B. diameter = 42 cm

so, radius = 42 / 2 = 21 cm

$area \: of \: circle \: = \pi \: r {}^{2} \\ 22 \div 7 \times 21 \times 21 \\ = 22 \times 3 \times 21 \\ = 66 \times 21 \\ = 1386cm {}^{2}$

Area of circle when r = 20cm is 1257.14 cm

AND, Area of circle if d = 42cm is 1386cm

Here is ur right answer

Answer 2

Answer:

a)Area is 1256.637 sq cm

a)Area is 1256.637 sq cmb)Area is 1385.4 sq cm

Step-by-step explanation:

Given that

a) Radius of circle is 20cm

b) Diameter of circle is 42cm

To find

Area of circle

Solution

a)As we know that

$area \: of \: circle = \pi \times {radius}^{2}$42

hence

$\pi = 3.14$

we get

$area \: of \: circle = 3.14 \times {20}^{2}$

by multiplication we get

$area \: of \: circle = 1256.637 {cm}^{2}$

b) Diameter is 42cm

We know that radius is always half of diameter hence

$radius = \frac{diameter}{2} = \frac{42}{2} = 21cm$

now

$area \: of \: circle = \pi \times {21}^{2}$

by multiplication we get

$area \: of \: circle = 1385.44 {cm}^{2}$