Cylinder, finding r and stuff

mathsux · 2008-03-09 12:17:48

From the image attached, the outside square has side lengths of 30cm.

The radius of each of the circles is " r " cm.

Use the length of the rectangle (i.e circumference of the circular base) to find the possible values of " r ".

Height of cylinder = 30 - 4r
Length of cylindr = 2nr where n = pi.
T.Area of Square = 900 cm^2

Last edited by mathsux (2008-03-09 12:18:18)

John E. Franklin · 2008-03-09 15:13:39

0< r <4.774648293

r is restricted from getting too big, or the distance around the circle
will be bigger than 30cm.

Identity · 2008-03-09 15:23:21

John that will not work because

I think I got something different...

We need only be concerned with the widths.

1. The side length of the square is 30cm

2. The width for the two circles is

3. The width for one circle is

4. Hence, the radius of one circle is

We can solve for r:

This is a weird question... i need to look at it again

Last edited by Identity (2008-03-09 15:27:46)

John E. Franklin · 2008-03-09 15:57:24

The height of the cylinder is a left to right dimension in
the diagram. and the perimeter goes up and down in
the diagram. Hope that helps you out.

Identity · 2008-03-09 16:40:55

Oh, do you mean it is the net of a cylinder? Like a cut-out?

mathsux · 2008-03-09 18:24:23

its a net of the cylinder

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