Question

Find the perimeter of each circle. Use 3 for pi.

Answer 1

Part 1

We need to find the perimeter of a circle with a diameter of 18 inches.

The relation between the perimeter P and the diameter d is given by:

`P=\pi d`

Since d = 18 inches and we need to use 3 for π, we obtain:

`P=3\cdot18\text{ inches }=54\text{ inches}`

Therefore, the ribbon needs to be 54 inches long.

Part 2

We need to find the perimeter of a semicircle with a radius of 8 in.

The perimeter of this semicircle is the sum of half the perimeter of the whole circle and the line segment formed by two radii.

The relation between the perimeter P and the radius r of a circle is:

`P=2\pi r`

Thus, half the perimeter is:

`(P)/(2)=\pi r`

Since we need to use 3 for π and r = 8 in, we obtain:

`(P)/(2)=3\cdot8\text{ in }=24\text{ in}`

And the line segment measures:

`2\cdot8\text{ in }=16\text{ in}`

Therefore, the perimeter of the calzone is:

`24\text{ in }+16\text{ in }=40\text{ in}`

Answer: 40 in.