Another Simple Math problem....

[cmbehan]

Basically I have an equation where values A, B, and C are always known and it calculates D.

Now I'm looking to do some hypotheticals and in doing that, I'd like to calculate for A, B, or C, if the other three are known.

Here's the D equation....

D=(A^2)/((A^2)+(B^2))*C

Can anyone lend a helping hand?

Thanks a ton!

 

[hypn0tik]

Is C supposed to be in the denominator? i.e.

A^2
------------------------
(A^2+B^2)*C

If so...

C = (A^2)/((A^2+B^2)*D)

A = sqrt(-B^2/(1 - 1/CD))

B = sqrt(A^2*(1/CD - 1)) = A*sqrt(1/CD - 1)

Edit: This might make it more clear.

Pic

 

[cmbehan]

Originally posted by: hypn0tik
Is C supposed to be in the denominator? i.e.

A^2
------------------------
(A^2+B^2)*C

If so...

C = (A^2)/((A^2+B^2)*D)

A = sqrt(-B^2/(1 - 1/CD))

B = sqrt(A^2*(1/CD - 1)) = A*sqrt(1/CD - 1)

Edit: This might make it more clear.

Pic

Thanks, but I screwed that one up......

C is not in the denominator.

It should have been:

D=[(A^2)/((A^2)+(B^2))]*C

 

[CycloWizard]

A=+/- b sqrt(d)/sqrt(c-d) with the caveat that b^2 d/(c-d)>=0

B=+/- A sqrt(c-d)/sqrt(d) with a^2 (c-d)/d>=0

C=(A^2+B^2)D/A^2

 

[hypn0tik]

Originally posted by: cmbehan

Originally posted by: hypn0tik
Is C supposed to be in the denominator? i.e.

A^2
------------------------
(A^2+B^2)*C

If so...

C = (A^2)/((A^2+B^2)*D)

A = sqrt(-B^2/(1 - 1/CD))

B = sqrt(A^2*(1/CD - 1)) = A*sqrt(1/CD - 1)

Edit: This might make it more clear.

Pic

Thanks, but I screwed that one up......

C is not in the denominator.

It should have been:

D=[(A^2)/((A^2)+(B^2))]*C

Ah. No worries. I would trust CycloWizard's answer even though I haven't checked it myself. He seems to know his stuff really well.

 

[CycloWizard]

Originally posted by: hypn0tik
Ah. No worries. I would trust CycloWizard's answer even though I haven't checked it myself. He seems to know his stuff really well.

I got lazy and let my calculator do this one for me, so hopefully it's right.