Can you help me derive the formula of this? I'm quite confused. :S

http://i50.tinypic.com/30moc2g.jpg

Question

Can you help me derive the formula of this? I'm quite confused. :S

http://i50.tinypic.com/30moc2g.jpg

lgbasallote · Answer

formula for surface area of a sphere?

anonymous · Answer

I know Pappus' 1st law will help me resolve this, but is it possible for a half ellipse if rotated to form a circle at the top?

anonymous · Answer

anyone? :(

kinggeorge · Answer

If you were to rotate half of the ellipse around the y-axis or the x-axis, it should give you the surface area.

anonymous · Answer

yes. Can I really form a circle at the top if I were to rotate it? :S

kinggeorge · Answer

You sure could. However, if I think about it, I'm pretty sure you have to rotate it around the y-axis, and not the x-axis.

anonymous · Answer

ahh. now I think of mentos. lol. hmm. I'll give it a try. I will revive this post in case I get stuck or whatever. XD