• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

An easier (but still good) math problem to test your geometry skills.

link

and the area between the circles?
it's "the area of the big circle minus the area of the small circle" square inches 😛

naaa... i'm too lazy to be thinking at this point 🙂

-529-
 


<< NO, im not doing your homework. 😉 >>



This is sarcasm, right?

*jothaxe shuffles to replace the batteries in his sarcasm-meter*
 
why the hell are we supposed to solve math problems here? you are missing school or something ? 🙂
 
/* it's &quot;the area of the big circle minus the area of the small circle&quot; square inches */

Well, it's not quite that simple. The solution will probably involve some trig, which since I haven't studied that yet, I don't have the slightest idea how to do 🙂
 
just something to do.

I have no idea jothaxe, but I think pi(r2) has something to do with it. actually that's for figuring the volume of a sphere isn't it? anyway.

Concentric just means they have the same center correct?
 


<< why the hell are we supposed to solve math problems here? you are missing school or something ? 🙂 >>



Pathetic though it may sound, I am missing it. 🙁 I get pretty bored during the summer, so I like to try to keep my reasoning skilled sharp. 🙂

And actually I started this thread at the request of Quaggoth.

-jothaxe
 
Well then wtf doesn't somebody just pull up that calculator buried deep in the start menu and figger the dang thing out? 😀
 


<< Concentric just means they have the same center correct? >>



Correct



<< I think pi(r2) has something to do with it. actually that's for figuring the volume of a sphere isn't it? >>



Actually, spheres have volume (4/3)*pi*r^3.

The area of a circle is just pi*r^2 as you said.

And the problem uses only a small amount of geometry and algebra. Once you see the trick the algebra is very brief.
 


<< Is the answer just Pi?
If it's correct I'll post my working. >>



Yes, this is the correct answer. And very quickly too. 🙂
 
without looking at the rest of your answers (honestly) the answer is Pi.

good little problem. i love math like this.
 
Pretty easy, here's what I did to get ~3.14159265359 inches.

1) Let R = the radius of the larger outside circle, and r = the radius of the smaller circle on the inside.

2) Find an equation to relate R to r. Do this by drawing a triangle. Draw a line from the center point to the left end of the line segment (note that this line equals the value &quot;r&quot😉, and see the triangle. You have a triangle with two sides of length r and 1, and a hypotenuse of length R. Pythagorean theorem shows that R = sqrt(r^2 + 1) obviously.

3) Area of space between circles = pi*R^2 - pi*r^2 = pi(R^2 - r^2). Substitute sqrt(r^2 + 1) for &quot;R&quot; in this formula and the r's cancel out, leaving you with pi.

A little too easy..
 
You must log in or register to reply here.

TRENDING THREADS

Back
Top