Question

1.

The area of ​​a circle is 25m^2, what would be its diameter?

2.
The perimeter of a circle is 30 cm, what would be its radius?

3.
What would be the area of ​​a circle with a perimeter of 12 feet.

HELP

Answer 1

1. diameter=5.54m

2. radius=9.55cm

3. area=11.46feet²

Explanation:

1. The formula of the area of a circle is: A=
`\pi r^(2)`

A: area of the circle=25m²

`\pi` : Pi≈3.14

r: radius of the circle= unknown

Solve the equation to find r:

25=(3.14)r²

r²=
`(25)/(3.14)` =7.69m²

r= √7.69= 2.77m

diameter d= 2 x r =2 x 2.77 =5.54m

2. The formula of the perimeter of a circle is: P=2
`\pi r`

P: perimeter of the circle= 30cm

`\pi` : Pi≈3.14

r: radius of the circle= unknown

Solve the equation to find r:

30=(3.14)r

r=
`(30)/(3.14)` = 9.55cm

radius r = 9.55cm

3. First we have to find r (radius) from the equation of perimeter:

P=2
`\pi r`

r=
`(P)/(2\pi )` =
`(12)/(2(3.14))` =
`(12)/(6.28)` =1.91 feet

Substitute r in the equation of area to get the area:

A=
`\pi r^(2)` = 3.14 (1.91)² = 3.14(3.65) = 11.46 feet²