Question

Someone explain please!

Answer 1

Here's the formula to find area of a circle

`\boxed{a= \pi * r^(2)}`
And here's the formula to find circumference of a circle

`\boxed{c=2 * \pi * r}`

Number 1
Find the area
a = π × r²
a = π × 4²
a = π × 16
a = 16π
The area of the first circle is 16π ft²

Find the circumference
c = 2 × π × r
c = 2 × π × 4
c = 8π
The circumference of the first circle is 8π ft

Number 2
The radius is not known yet. We have to find the radius from the diameter. Radius is half of the diameter.
r =
`(1)/(2)` × d
r =
`(1)/(2)` × 13
r =
`(13)/(2)`

Find the area
a = π × r²
a = π ×
`( (13)/(2)) ^(2)`
a = π ×
`( (169)/(4))`
a =
`(169)/(4) \pi`
The area of the second circle is
`(169)/(4) \pi` m²

Find the circumference
c = 2 × π × r
c = (2r) × π
remember radius is half of diameter, 2 radius equals a diameter
c = d × π
c =13 × π
c = 13π
The circumference is 13π m

Answer 2

well the circumference is the distance around a circle so what you would do is multiply by the 4x2 to get the diameter and then you’d multiply 8x3.14 or wtv your teacher told you to use for pi either 3 or 3.14