What is the missing length? p 18.6 mi area=286.44 mi2

Aria = w * i
Good luck

Meters. 1 m is equivalent to 1.0936 yards, or 39.370 inches. Since 1983, the metre has been officially defined as the length of the path travelled by light in a vacuum during a time interval of 1/299,792,458 of a second.

To convert a foot measurement to a nanometer measurement, multiply the length by the conversion ratio. One foot is equal to 304,800,000 nanometers, so use this simple formula to convert:
1 ft = 304,800,000 nm
nanometers = feet × 304,800,000
The length in nanometers is equal to the feet multiplied by 304,800,000.
For example, here's how to convert 5 feet to nanometers using the formula above. 5' = (5 × 304,800,000) = 1,524,000,000 nm

feet X feet = square feet
That's it.

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.