Wednesday, May 25, 2011

12.6- Surface Area and Volume of Spheres

     http://www.youtube.com/watch?v=moBGSB3ohc0&feature=channel_video_title

       I didn’t know anything before watching the video besides knowing what a sphere is, but that doesn’t really help with anything. So, that is pretty much everything I knew before watching the video.
      What I learned after watching the video was how to find the surface area of a sphere. The equation is surface area equals four times pi times radius squared, or S.A=4πr^2.  I also learned what great circles are. A great circle is a circle where the circumference is 13.8π. You can use the great circles to find the surface area of spheres. I also learned how to find the surface area of a hemisphere. You use the equation S=1/2(4πr^2) +πr^2.  Another thing that I learned is how to find the volume of a sphere. To find the volume of a sphere you use the equation volume equals four thirds time pi time radius to the square root of three, or V=4/3πr^3. You can use the equations volume of a cylinder (πr^2h) and the volume of a sphere (4/3πr^3) to find the volume of a cylinder with two spheres on both ends. To find the volume you have the volume of a cylinder minus the volume of sphere. So, since the height equals 12 radius equals 5, you get the volume to equal about 418.879.

Word Count: 217

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