# One of them math problems

Discussion in 'Random Discussion' started by Big-K, Jan 24, 2005.

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Brain freeze. You have a regular n-gon. You know that all the interior angles are 144 degrees. What is the value of n?(n is the number of sides). Sofar I have 144n/n-2=180. I then simplified that to 144n=180n-360 by multiplying both sides by n-2 and distributing it on the right side. I can't seem to figure out where to go from here...

2. ### DiSaidSo

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42

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I'll believe that, but that means that my formula is wrong, which is proven by the fact that it doesnt work on other problems either.

4. ### DiSaidSo

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K~

I really have no idea. My math is pretty rusty. What you said might as well have been in Japanese.

~Di

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damn

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Alright, i'm sure my forumla is right, although i changed it to 144n=180(n-2)

7. ### Raeli

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144n=180n-360
-144n, +360
360=36n
/36
10=n

I think.

It's been a while.

8. ### DiSaidSo

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Damn, Raeli. That was HOT!

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wow...that makes sense

Now I gotta do that, but this time I get the measure of the EXterior angles

10. ### Raeli

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It's about time math did something for me other than balance my checkbook!

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Thats what calculators are for. Calculators can't do geometry.

12. ### LuckyStrike

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If you know the interior angle and want to solve for the number of sides, then:

N=360/(180-A)

Where N is the number of sides to the polygon and A is the interior angle between adjacent sides.

If you know the number of sides and want to solve for the interior angle then:

A=180-(360/N)

These formulas are only valid for regular polygons, of course.

13. ### jmosmith

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The sum of all the internal angles in any closed Polygon
= (180 * # of sides) - 360

The number of internal angles in any closed Polygon, is equal to the number of sides.

If we let N="# of sides"
Then the equation becomes:

144*N = 180*N - 360

Solving for N:

360 = 180*N - 144*N
360 = (180 - 144)*N
360 = 36*N
360/36 = N
10 = N

So I can CONFIRM Raeli's answer.

If you look above, you will also see the derivation of the equations cited by LuckyStrike.

Hope this helped

Got any more???

thanks,
J

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Yeah, I remembered later that the exterior angles of any polygon are always 360 degrees. I ended up finishing it perfectly.