# Figuring square footage **URL:** \ **Category:** Factual Questions\ **Created:** [May 11, 2001, 5:31am UTC](https://boards.straightdope.com/t/figuring-square-footage/65071 "2001-05-11T05:31:13Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![JillGat](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JillGat](https://boards.straightdope.com/u/JillGat)\ **Post date:** [May 11, 2001, 5:31am UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/1 "2001-05-11T05:31:13Z")
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. ---
**Author:** ![Trucido](https://avatars.discourse-cdn.com/v4/letter/t/ea5d25/32.png) [@Trucido](https://boards.straightdope.com/u/Trucido)\ **Post date:** [May 11, 2001, 5:37am UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/2 "2001-05-11T05:37:06Z")
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. ---
**Author:** ![mangeorge](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@mangeorge](https://boards.straightdope.com/u/mangeorge)\ **Post date:** [May 11, 2001, 5:37am UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/3 "2001-05-11T05:37:49Z")
Don’t know how to do the symbols, but it’s pi x radius squared, divided by four. Right? Peace, mangeorge ---
**Author:** ![rowrrbazzle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rowrrbazzle/32/414_2.png) [@rowrrbazzle](https://boards.straightdope.com/u/rowrrbazzle)\ **Post date:** [May 11, 2001, 5:41am UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/4 "2001-05-11T05:41:18Z")
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. ---
**Author:** ![mangeorge](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@mangeorge](https://boards.straightdope.com/u/mangeorge)\ **Post date:** [May 11, 2001, 5:46am UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/5 "2001-05-11T05:46:46Z")
I’d say you got about, oh, say 284 sq. ft. 😉 Peace, mangeorge ---
**Author:** ![JillGat](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JillGat](https://boards.straightdope.com/u/JillGat)\ **Post date:** [May 11, 2001, 5:49am UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/6 "2001-05-11T05:49:47Z")
Hey, thanks guys! Now who’s gonna come help me shovel these rocks? ---
**Author:** ![mangeorge](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@mangeorge](https://boards.straightdope.com/u/mangeorge)\ **Post date:** [May 11, 2001, 5:56am UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/7 "2001-05-11T05:56:01Z")
> [@](#): > > \*Originally posted by JillGat \* > \*\*Hey, thanks guys! Now who’s gonna come help me shovel these rocks? \*\* Whoops! I think I hear my mother calling. 😃 Peace, mangeorge ---
**Author:** ![Coldfire](https://avatars.discourse-cdn.com/v4/letter/c/a587f6/32.png) [@Coldfire](https://boards.straightdope.com/u/Coldfire)\ **Post date:** [May 11, 2001, 10:14am UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/8 "2001-05-11T10:14:32Z")
Dudes, check out [Jills physique](http://www.geocities.com/sdpeoplepages/jillgat.html). 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. 😉 ---
**Author:** ![dewt](https://avatars.discourse-cdn.com/v4/letter/d/9dc877/32.png) [@dewt](https://boards.straightdope.com/u/dewt)\ **Post date:** [May 11, 2001, 11:01am UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/9 "2001-05-11T11:01:17Z")
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 ---
**Author:** ![Spritle](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@Spritle](https://boards.straightdope.com/u/Spritle)\ **Post date:** [May 11, 2001, 11:54am UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/10 "2001-05-11T11:54:06Z")
**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. ---
**Author:** ![Olentzero](https://avatars.discourse-cdn.com/v4/letter/o/90ced4/32.png) [@Olentzero](https://boards.straightdope.com/u/Olentzero)\ **Post date:** [May 11, 2001, 2:12pm UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/11 "2001-05-11T14:12:25Z")
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.) ---
**Author:** ![JillGat](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JillGat](https://boards.straightdope.com/u/JillGat)\ **Post date:** [May 11, 2001, 2:43pm UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/12 "2001-05-11T14:43:01Z")
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 ---
**Author:** ![Race\_Bannon](https://avatars.discourse-cdn.com/v4/letter/r/5f8ce5/32.png) [@Race\_Bannon](https://boards.straightdope.com/u/Race_Bannon)\ **Post date:** [May 12, 2001, 1:44pm UTC](https://boards.straightdope.com/t/figuring-square-footage/65071/13 "2001-05-12T13:44:23Z")
[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]