Third grade equation

[Diana]

Hi,

I need help with a third gtade equation. I don´t know if excel can
help me with this. I have this equation

V=l·(r^2·COS((r - h)/r)^(-1) - (r - h)·SQRT(2·h·r - h^2))
..
Where

V=volume
l = large
r= radio
h= is the vakue I need to know

If I do it with my calculator Texas TI-89 it gives me these values:

V = 36,855
l = 5
r = 2,53
h= 1,9999999

The V, I and R values are constantly modified. How can I solve de H
variable.

I´ve tried with soolver bit by bit but I get nothing.


Thank you so much

 

[Joe User]

I´ve tried with soolver bit by bit but I get nothing.

You neglect to say what version of Excel you are using. I had no problem
getting a solution using Solver in Excel 2003 SP3.

V = 36,855
l = 5
r = 2,53
h= 1,9999999

I set up 3 cells named vol (V), rad (r), len (l), and hgt (h).

I put 5 into the cell named len and 2.53 into the cell named rad. Note: I
use period as the radix point, where I believe you use comma.

In the cell named vol, I put the following formula:

=len*rad / (rad^2 * COS(rad-hgt))
-(rad-hgt)*SQRT(2*hgt*rad - hgt^2)

That is intended to be the same as your formula. I just rearranged some
terms to simplify it. If I made errors, I assume you can correct them.

In Solver, I set Target Cell to vol with Equal to Value set to 36.855. I
set the Changing Cells to hgt. I also added the constraint hgt >= 0,
although I don't know if that is necessary.

Solver's solution: hgt is about 1.008717.

PS: They must have a very advanced "third grade" in your country ;-).


----- original message -----

Hi,

I need help with a third gtade equation. I don´t know if excel can
help me with this. I have this equation

V=l·(r^2·COS((r - h)/r)^(-1) - (r - h)·SQRT(2·h·r - h^2))
..
Where

V=volume
l = large
r= radio
h= is the vakue I need to know

If I do it with my calculator Texas TI-89 it gives me these values:

V = 36,855
l = 5
r = 2,53
h= 1,9999999

The V, I and R values are constantly modified. How can I solve de H
variable.

I´ve tried with soolver bit by bit but I get nothing.


Thank you so much

 

[Diana]

Thank you very much. That was great help for me.

You neglect to say what version of Excel you are using.  I had no problem
getting a solution using Solver in Excel 2003 SP3.


I set up 3 cells named vol (V), rad (r), len (l), and hgt (h).

I put 5 into the cell named len and 2.53 into the cell named rad.  Note:  I
use period as the radix point, where I believe you use comma.

In the cell named vol, I put the following formula:

=len*rad / (rad^2 * COS(rad-hgt))
-(rad-hgt)*SQRT(2*hgt*rad - hgt^2)

That is intended to be the same as your formula.  I just rearranged some
terms to simplify it.  If I made errors, I assume you can correct them.

In Solver, I set Target Cell to vol with Equal to Value set to 36.855.  I
set the Changing Cells to hgt.  I also added the constraint hgt >= 0,
although I don't know if that is necessary.

Solver's solution:  hgt is about 1.008717.

PS:  They must have a very advanced "third grade" in your country ;-).

----- original message -----


Hi,

I need help with a third gtade equation. I don t know if excel can
help me with this. I have this equation

V=l (r^2 COS((r - h)/r)^(-1) - (r - h) SQRT(2 h r - h^2))
.
Where

V=volume
l = large
r= radio
h= is the vakue I need to know

If I do it with my calculator Texas TI-89 it gives me these values:

V = 36,855
l = 5
r = 2,53
h= 1,9999999

The V, I and R values are constantly modified. How can I solve de H
variable.

I ve tried with soolver bit by bit but I get nothing.

Thank you so much