find sruface area of sphere with cube inside with edge=1  TOPIC_SOLVED

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find sruface area of sphere with cube inside with edge=1

Postby king&i on Sun Jul 19, 2009 12:22 pm

problem- cube in a shpere edge of cube=1
i need to find teh surface area of the sphere??
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Re: find sruface area of sphere with cube inside with edge=1

Postby Honeysuckle588 on Mon Jul 20, 2009 12:19 pm

In order to find the surface area of the sphere, you need to find know its radius. You will use the cube to determine the radius of the sphere. Since the cube is inscribed in the sphere, the center of the cube and the center of the sphere coincide.

Also, since the cube is inscribed inside the sphere, the corners of the cube touch the sphere. Consequently, if you determine the distance from the center of the cube to one of its corners, you will have found the radius of the sphere.

I can provide a lot more help, but I don't want to solve the problem for you. Let me know if you need more guidance.
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Re: find sruface area of sphere with cube inside with edge=1

Postby king&i on Mon Jul 20, 2009 4:12 pm

how do u use the cube to find the radius????
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Re: find sruface area of sphere with cube inside with edge=1

Postby Honeysuckle588 on Mon Jul 20, 2009 6:08 pm

Do you agree that the radius of the sphere is the same as finding the distance from the center of the cube to one of its corners?
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Re: find sruface area of sphere with cube inside with edge=1

Postby king&i on Fri Jul 24, 2009 4:21 pm

i guess i hadnt looked at it that way
that helps me picture it but still dont no how 2 find r??
tryed drawing it but cant get numbers??
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  TOPIC_SOLVED

Postby stapel_eliz on Fri Jul 24, 2009 6:29 pm

Go from the center up to the top of the cube. How long is this?

Go from the center of the top of the cube to one corner. How long is this?

These two lengths form the two sides of a right triangle, with the distance from the center to the corner being also the radius. Apply the Pythagorean Theorem. :wink:
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Re: find sruface area of sphere with cube inside with edge=1

Postby king&i on Tue Jul 28, 2009 4:46 pm

ill try that
thnx
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