Question

Find the circumference of each of the following circles. Use 22 for TT.

22 cm
7 in
40 mi
15 yd

Answer 1

A)
`(484)/(7)`cm

B)
`44`in

C)
`(880)/(7)`mi

D)
`(660)/(7)`yd

Explanation:

The formula for the circumference of a circle is:

`C=2\pi r`

Within the problem it is stated to use
`(22)/(7)` for
`\pi` so our equation will be:

`C=2(22)/(7)r` which simplifies to
`C=(44r)/(7)`

The variable
`r` in the equation for the circumference represents 'radius' which is half the diameter, for circle's A and C we are given a diameter. We can divide these numbers in half to get a radius. From there we plug in each radius to get circumference of each circle!

A)

`\text{Diameter}=22\\\text{Radius {\it (r)}}=\frac{\textit{diameter}}{2}=(22)/(2)=11\\\text{Circumference}=(44(11))/(7)=(484)/(7)`

B)

`\text{Radius {\it (r)}}=7\\\text{Circumference}=(44(7))/(7)=(308)/(7)=44`

C)

`\text{Diameter}=40\\\text{Radius {\it (r)}}=\frac{\textit{diameter}}{2}=(40)/(2)=20\\\text{Circumference}=(44(20))/(7)=(880)/(7)`

D)

`\text{Radius {\it (r)}}=15\\\text{Circumference}=(44(15))/(7)=(660)/(7)`

Remember to include units of measurement in your answers.