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zkphill

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The formula A=2*pi*r^2+2*pi*r*h, is the formula...

The formula A=2*pi*r^2+2*pi*r*h, is the formula for the surface area of a cylinder. An article on math.com goes into more detail of how this formula works. The u.r.l. is, http://www.math.com/tables/geometry/surfareas.htm . To solve for r, first rearrange as 2*pi*r^2+2*pi*r*h=A. Divide by 2pi giving r^2+r*h=A/2pi. Since a^2+2ab+b^2 = (a+b)^2 to complete the square in r^2+r*h, we add (h/2)^2 to both sides, r^2+r*h+h^2/4=A/(2pi)+h^2/4. Next we factor the left side as (r+h/2)^2 combine the fractions on the right, 2*A+pi*h^2/4*pi and squaring both sides gives us, r = sqrt(2*A+pi*h^2/4*pi)-h/2. Comments and or corrections are welcomed. Continue reading

Posted Dec 27, 2009 at zkphill's blog

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Since thanksgiving is tomorrow I think I'll make...

Since thanksgiving is tomorrow I think I'll make my first blog post on what I am thankful for. The one one thing that I am the most thankful for other than the ability to feel and experience gratitude would probably be experiencing other people's gratitude for having done something meaningful or generous. For everything we have to be thankful for there is at least one faithful person behind the scenes doing something that will probably never get noticed. I think this is the best place to be. Continue reading

Posted Nov 25, 2009 at zkphill's blog

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zkphill is now following Jeff Lilley

Nov 25, 2009

Welcome to TypePad! This is a sample post you can...

Welcome to TypePad! This is a sample post you can edit or delete later. Continue reading

Posted Nov 21, 2009 at zkphill's blog

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zkphill is now following The Typepad Team

Nov 21, 2009

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