As an epidemiologist, I’m embarrassed to post this simple math question. Not that embarrassed, apparently…
I have a section of yard that I want to buy rocks for, and I want to figure out the square footage of the area. It’s a quarter of a circle, and the right angles are 19 ft.x 19 ft. I built a semi-circle wall 19 ft. out from the corner, in other words. I know pi figures into this, but I can’t remember how.
Easy, even without an arc-length formula. Figure the area of the circle with the pi r squared, then divide by four. The answer should be 283.38 square feet.
Don’t know how to do the symbols, but it’s pi x radius squared, divided by four. Right?
Peace,
mangeorge
area of a circle = pi*r[sup]2[/sup]
You have 1/4 of a circle. The radius is 19 ft.
Therefore your area = 1/4 * pi * 19[sup]2[/sup] sq. ft.
= pi * 1/4 * 19[sup]2[/sup] sq. ft.
= pi * 90.25 sq. ft.
= approximately 283.5287 square feet.
I’d say you got about, oh, say 284 sq. ft.
Peace,
mangeorge
Hey, thanks guys! Now who’s gonna come help me shovel these rocks?
Whoops! I think I hear my mother calling. 
Peace,
mangeorge
Dudes, check out Jills physique. That lady doesn’t need any help shoveling rocks. In a bar fight, she’d probably beat the crap out of the lot of us.
er… as a professional rock shoveller, I’d like to reasure you that your question is not as simple as you might think. Math is different when you are calculating materials for a construction job.
Particularily stone.
You’re looking at about 300-312 sq feet, depending on what kind of stone we’re talking about. You’ll have some left over, but trust me, it’s better this way.
dewt
Dewt is right. Some funky stuff happens to math when calculating for home improvement. I had to fill a trench 75 feet long and 1 foot wide with gravel to 1 foot deep. One would think this would require
75 feet x 1 foot x 1 foot = 75 feet[sup]3[/sup] of gravel.
This equals
75 feet[sup]3[/sup]/ 27 feet[sup]3[/sup]= 2.8 cubic yards
So, rounding up, I buy 3 cubic yards of gravel and run out:mad: with about 5 feet to go! It’s weird I tells ya.
Screw this rock-shovelling, area-calculating crap!
Jill got a portrait done by Slug.
If that doesn’t give you god-like status, I don’t know what does.
(Hijack ended. You may now move freely about the cabin. Please cooperate with the heavily armed special-forces agents who will be momentarily bursting through the exit door to liberate you. Thank you, and have a pleasant day.)
I built the wall by myself, too. Bunch of guys on racing bikes stopped by and I gave them beers and they stood in the driveway talking about derailleurs, drinking beer, and watching me work. I guess they were afraid that carrying those blocks would cause snags in those spandex bicycle shorts. - Jill
[niggle] The quarter circle you describe is known as a quadrant. A semi-circle is half of a circle. The general term for a pie wedge is sector.[/niggle]