For Mrs. S.: Area of a circle!
Click on the graphic above to see simple proof that A = Pi * r-squared for a circle! As mentioned in my note to Johnny and Mr. P. on July 8 (below), Pi is defined to be the circumference of a circle divided by its diameter, of course. I guess you would have to know that 2 * r = d, but everyone knows that, right?
posted by Dr. Joe @ 11:36 AM
8 comments
8 Comments:
Dr. Joe,
Your proof assumes the average height of the pie slices from the original circle is the radius. That is a reasonable assumption but perhaps should be proven too.
Thank you for posting a solution,
Mrs. S.
Simply note that each pie slice is symmetrical about its bisector, Mrs. P. QED
Apologies, Mrs S. (I misspelled your surname in my previous posting!) Dr. J.
Its to confusing for me, but I am willing to learn if someone out their is willing to teach me. Your never to old to learn, right? From someone who is teachable from out of this world and beyond
It's fantastic more people want to learn these math proofs.
Dr. Joe, can you prove out how the size of the earth was first calculated by scientists without all the technology we have now today?
Thank you,
Mrs. S.
Mrs. S.: That's easy! They dug a hole to the center, measured its depth, then muliplied by 2^Pi.
I assume that by "how big" you meant "what's the earth's circumference?"
As regards digging the hole, BP is trying to replicate that feat in the Gulf.
Quick correction to previous comment: one would mutiply the depth of the hole to the center of the earth (see Jules B.) them multiply by 2 x Pi, of course. not 2^Pi.
That's Jules Verne, not Jules B.!
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