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#1 2010-06-20 01:49:58
- lakeheadca
- Member
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Find diameter
how to find the diameter of the given figure.
thank you so much guys, specially bobby who always help so fast. He is great.
#2 2010-06-20 03:45:06
- bobbym
- Administrator
Online
Re: Find diameter
specially bobby who always help so fast. He is great.
Yea, he is, when I grow up I want to be him.
We need to find r of the small circle. Fortunately there is a relationship that does all the work. There is an easier one that relates r to the heights but I am too lazy to look for it.
Where B1 is the area of the smaller circle. B2 is the area of the larger circle. h1 = height from the apex to smaller circle and h2 to the larger.
Do you see that it contains the little r we need. Like magic.
Cross multiply:
Divide both sides by pi.
Divide both sides by 144:
r = 6 and r = -6
Can't have a radius of - 6 so r = 6 and d = 2r = 12.
diameter of smaller circle is 12
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.
#4 2010-06-21 03:12:30
- bobbym
- Administrator
Online
Re: Find diameter
Hi lakeheadca;
Glad to help. Bring more!
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.