The perimeter of a semicircle is 5.14 miles. What is the semicircle radius?

2r=diameter

Oh wow, lots of math going on here...

There are 4840 square yards in an acre and 9 square feet in a square yard (4840 x 9 = 43,560).

An acre is an old timers measurement used in agriculture...
it was 4 poles wide and 40 poles long. A pole is equivalent to sixteen and a half feet. So back then, an acre was a piece of farming land 660 feet long (220 yards or one eighth of a mile) and 66 feet wide (22 yards or one eightieth of a mile).

Acre is a measure of area, which would be square feet.

Feet are a measure of distance.

The best you could do is something like this:
An acre is 43, 560 square feet.
Draw/imagine a square or a rectangle that would cover that much area.

If it is a square, it would be (approximately) 208.7 feet on each side.

Its perimeter (the distance around it if you walk an imaginary fence around you acre-sized plot) would be 834.8 feet.

Trying to to figure out an acre of 'Circle' - hmmmmm???

Radius = 1/2 of Diameter

sorry, just can't wrap my head around this to come up with the correct equation.
maybe we can get lucky with some other brainiac taking what I did provide and come up with a solution for you?

Square - It would be 208.7 feet across if you walk across it, and the same if you walk the other way across it.

What is the question?
A circle with a radius of 3 kilometers has a perimeter of about 18.85 kilometers and an area of about 28.27 square kilometers.

You add the measure of all the sides for a polygon. For a circle of radius r, the perimeter is 2*Pi*r

3 3rd pie * the radius cubed for a sphere

3 3rd pie * the radius squared x the height squared for a cone

3 3rd pie * the perimeter squared x the peak squared for a pyramid

discs are a standard size 120mm in diameter so 60mm radius
http://en.wikipedia.org/wiki/Compact_Disc

Hello,
You must have been taught the relation between the circumference (perimeter) of a circle, the radius and pi. Use it to calculate the perimeter. It is true for all circular figure.
Depending on what is really asked (the perimeter of the actual pool where you find the water, or the general pool area where no shoes are allowed)
1st case: use the radius that was given.
2nd case: the total radius is the radius given plus the width of the path.

If you do not have a formula for the perimeter that involves the radius, but have one that involves the diameter you can use it too, knowing that the diameter is twice the radius or the radius is one half of the diameter.

As you might have guessed I was not going to make things too easy for you by providing a ready-made answer, but I gave you all the hints that will help you solve the problem.

You cannot have a semicircle that has a diameter of 2.500 mm and a radius of .425mm and a circumference of 3000mm

Circumference is equal to pi times the diameter. pi is = 3.14

The radius of a circle is always 1/2 the diameter

Area of a circle is pi time the radius squared


Loringh

1.3x10to the power of -12

This sounds like someones homework. I'm risking my reputation here but here goes.

Previous Area was Pi x R x R. = Pi X 10 X 10 = 100 X Pi
Previous Perimeter is 2 X Pi X R = 2 X Pi X 10 = 20 X Pi

New shape is a rectangle with a semicircle at each end and width of 10 cm.
New Perimeter is circular bits + straight edges between them.
We know the circular bits but not how long the straight bits are so ...
Perimeter = 20 X Pi = (2 X Pi X 5) + L X 2 = 10 X Pi + (L X 2)
So L = (20 - 10) X Pi / 2 = 5 X Pi.

So the new Area is ... (Pi X 5 X 5) + (10 X 5 X Pi)
= 75 X Pi.
= 75 X 3.14 = 235.5