CONE-FRUSTRUM

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Hy!!

Please help!!
If there is a cone with a side 4/sq rt(3) and if we cut cone parallel with a base then we get a two cone (parts) with same volume. What is the height from base to cut part (frustrum).

The results are :A) sqrt(2)/2
B) 2-CUBE ROOT(2)
C) CUBE ROOT(4)/2
D) SQRT(3)/2
E) 2-CUBE ROOT(4)
WHICH ONE IS TRUE???
Thanks!!

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Type: Discussion • Score: 1 • Views: 692 • Replies: 3

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Tell us what you already know about this problem, and we will help you where you are having problems (I don't like to do homework that I don't get a grade for, but I don't mind helping).

Do you have an equation for the volume of a cone?

Do you have an equation for the volume of a cone part (cut with no tip?

(If you have the first, you should be able to get the second by simply subtracting a small cone from a bigger one.

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Re: CONE-FRUSTRUM

muki wrote:

Hy!!

Please help!!
If there is a cone with a side 4/sq rt(3) and if we cut cone parallel with a base then we get a two cone (parts) with same volume. What is the height from base to cut part (frustrum).

The results are :A) sqrt(2)/2
B) 2-CUBE ROOT(2)
C) CUBE ROOT(4)/2
D) SQRT(3)/2
E) 2-CUBE ROOT(4)
WHICH ONE IS TRUE???
Thanks!!

R/r=H/h
1/3*Pi*R^*h=2*1/3*Pi*r^2*h
h/H=R^2/2*r^2=1/2(R/r)^2
h/H=1/2(H/h)^2=h/H=H^2/2*h^2
h^3=1/2H^3
h=1*H/cube root(2)

H-1/cube root(2)*H=(1-1/CUBE ROOT(2))*H

This is what I` get but it is not right ,can you help now

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One problem is that you are using "H" for the height of the cone. The problem gives you the length of a side.

I might use Pythag. to get an expression for the side given r and h.

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