How do i calculate square miles in a circle?

[toekramp]

I was just asked by my boss how many square miles are in a circle that has a 340 mile diameter... anyone?

 

[meltdown75]

3.14 (170*170)?

I'm thinking pi * radius squared for some reason.

 

[dullard]

Area = pi*r^2.

You are done.

 

[toekramp]

i am dumb, thanks guys

 

[Auggie]

area of a circle = pi * radius^2

= 3.141 * 170^2

= about 90,774 square miles

 

[Fullmetal Chocobo]

Draw a picture, and count the squares.

 

[dullard]

Note: if you are talking land area, then the answer is far greater than pi*r^2. Why? Land is hilly, and hilly land has more surface area than a hypothetical perfectly flat circle.

In an area that large, you'll get lots of peaks and valleys if we are talking about Earth.

 

[pnad]

Correct 90792.03 Square Miles
pi*r^2

 

[AStar617]

Originally posted by: dullard
Note: if you are talking land area, then the answer is far greater than pi*r^2. Why? Land is hilly, and hilly land has more surface area than a hypothetical perfectly flat circle.

In an area that large, you'll get lots of peaks and valleys if we are talking about Earth.

beat me to it.

 

[So]

Originally posted by: toekramp
i am dumb, thanks guys

SRSLY.

Have another :beer: before lunch.

 

[CycloWizard]

Originally posted by: pnad
Correct 90792.03 Square Miles
pi*r^2

Wrong. 91,000 square miles. Sig figs.

 

[Heisenberg]

Originally posted by: CycloWizard

Originally posted by: pnad
Correct 90792.03 Square Miles
pi*r^2

Wrong. 91,000 square miles. Sig figs.

You're a damn chemist, aren't you?

 

[RapidSnail]

Originally posted by: CycloWizard

Originally posted by: pnad
Correct 90792.03 Square Miles
pi*r^2

Wrong. 91,000 square miles. Sig figs.

LOL, I was thinking the same thing!

 

[dullard]

Originally posted by: RapidSnail
LOL, I was thinking the same thing!

How much time would it take for a rapid snail to see most of that ~110,000 square miles (assuming reasonably bumpy terrain)? Are we talking superman rapid or molasis on a chilly day rapid?

 

[MercenaryForHire]

Originally posted by: dullard

Originally posted by: RapidSnail
LOL, I was thinking the same thing!

How much time would it take for a rapid snail to see most of that ~110,000 square miles (assuming reasonably bumpy terrain)?

African or European?

- M4H

 

[jlbenedict]

Originally posted by: dullard
Note: if you are talking land area, then the answer is far greater than pi*r^2. Why? Land is hilly, and hilly land has more surface area than a hypothetical perfectly flat circle.

In an area that large, you'll get lots of peaks and valleys if we are talking about Earth.

So, pi * r^2 really applies to just math theory, and 2d images instead of real world applications?

 

[ElFenix]

pie are round, cornbread are square

 

[jlbenedict]

Originally posted by: ElFenix
pie are round, cornbread are square

mmmmmm cornbread, fresh from the oven

 

[dullard]

Originally posted by: jlbenedict
So, pi * r^2 really applies to just math theory, and 2d images instead of real world applications?

Exactly.

Heck, even in 2-D images you can't acurately measure some things. Think about a coast line. How long is the waterfront property? If the coast is perfectly straight, that is a simple question. If the property is complex like a normal beach, then that answer is very difficult. The more fine your resolution, the greater the length (to a point). You'd have to count grains of sand if you wanted the true length, and no one has ever done that. Thus, coastline measurements are still increasing every time someone does a more accurate measurement (because their resolutions are still far greater than the size of a grain of sand).

And, that has nothing to do with the change of length with tides or waves, I'm talking a static 2-D picture of the coast.

 

[DeadByDawn]

Originally posted by: jlbenedict

Originally posted by: dullard
Note: if you are talking land area, then the answer is far greater than pi*r^2. Why? Land is hilly, and hilly land has more surface area than a hypothetical perfectly flat circle.

In an area that large, you'll get lots of peaks and valleys if we are talking about Earth.

So, pi * r^2 really applies to just math theory, and 2d images instead of real world applications?

No, it has real world applications. A square mile on a map does not take into account fluctuations in elevation.

 

[dullard]

Originally posted by: MercenaryForHire
African or European?

- M4H

That made me laugh, one of the best movies ever. Lets use African Rapid Snails for this thread.

 

[Mermaidman]

Originally posted by: dullard
Note: if you are talking land area, then the answer is far greater than pi*r^2. Why? Land is hilly, and hilly land has more surface area than a hypothetical perfectly flat circle.

In an area that large, you'll get lots of peaks and valleys if we are talking about Earth.

What about legally?

 

[dullard]

Originally posted by: Mermaidman
What about legally?

I assume the laws make it a flat projection, smaller than the actual land area. But I don't know the laws, so that is just a reasonable assumption.

 

[spidey07]

I don't think square miles or area measurements of land care about topology changes. It's a measure of distance, not the distance as you walk it.

 

[mercanucaribe]

Originally posted by: AStar617

Originally posted by: dullard
Note: if you are talking land area, then the answer is far greater than pi*r^2. Why? Land is hilly, and hilly land has more surface area than a hypothetical perfectly flat circle.

In an area that large, you'll get lots of peaks and valleys if we are talking about Earth.

beat me to it.

Land area is never calculated like that AFAIK and I'm a geographer. An acre is a land unit on the datum not the 3d topography.

If you use the actual area of the terrain, you'd have to arbitrarily decide what resolution DEM to use. Areas would be different depending on whether you use 10m pixels, or 1cm pixels. If the pixels were infintely small, area for any section of land would be infinite, for the same reason that a coastline length continually gets longer as you increase resolution used to measure it.

For mineral rights it wouldn't matter, and for farming it would be moot because soil on a slope is less fertile. You can't build a tilted house either.