Question

1. D=7.4 calculate the area of the circle

2. R=2.2 yd
Calculate the circumference of the circle

3. D=5 cm
Calculate the circumference of the circle


4. D=6 cm
Calculate the circumference of the circle


5. R=2.1 m
Calculate the area of the circle



6. R= 1.3 mm
Calculate the circumference of the circle

Answer 1

`\qquad\qquad\huge\underline{{\sf Answer}}♨`

We need to know two formulas before we start ~

• Area of circle =
  `\sf \pi r²`

• Radius (r) = diameter (d) ÷ 2

• Circumference =
  `\sf 2\pi r \:\: or \;\;\pi d`

Taking value of pi as 3.14

Let's solve ~

problem 1

`\qquad \sf  \dashrightarrow \:d = 7.4`

`\qquad \sf  \dashrightarrow \:r = d / 2`

`\qquad \sf  \dashrightarrow \:r = 7.4 / 2`

`\qquad \sf  \dashrightarrow \:r = 3.7 \: \: units`

now,

`\qquad \sf  \dashrightarrow \:area = 3.14 * (3.7) {}^(2)`

`\qquad \sf  \dashrightarrow \:a = 42.9866 \approx43 \: \: unit {}^(2)`

problem 2

`\qquad \sf  \dashrightarrow \:r = 2.2 \: yd`

`\qquad \sf  \dashrightarrow \: circumference = 2 * 3.14 * 2.2`

`\qquad \sf  \dashrightarrow \: c =13.816 \: yd`

problem 3

`\qquad \sf  \dashrightarrow \:d = 5 \: cm`

`\qquad \sf  \dashrightarrow \:circumference = 3.14 * 5`

`\qquad \sf  \dashrightarrow \:c = 15.7 \: \: cm`

problem 4

`\qquad \sf  \dashrightarrow \:d = 6 \: cm`

`\qquad \sf  \dashrightarrow \:circumference = 3.14 * 6`

`\qquad \sf  \dashrightarrow \:c =18 .84 \: \: cm`

problem 5

`\qquad \sf  \dashrightarrow \:r = 2.1 \: m`

`\qquad \sf  \dashrightarrow \:area = 3.14 * (2.1) {}^(2)`

`\qquad \sf  \dashrightarrow \:a = 3.14 * 4.41`

`\qquad \sf  \dashrightarrow \:a \approx13.85 \: \: m {}^(2)`

problem 6

`\qquad \sf  \dashrightarrow \:r = 1.3 \: mm`

`\qquad \sf  \dashrightarrow \:c = 2 * 3.14 * 1.3`

`\qquad \sf  \dashrightarrow \:c = 8.16 \: \: mm`