# Help with solving three equations with 3 unknowns

1. Feb 12, 2014

### mechie-diva

I have the three following equations in the file attached:

1. 70000000=(((R1^3)*4/3)-((R2^3)*4/3 "))(100*cosα))/(2(R1 -R2)(pi/2)(R1^4-R2^4) + 100sinα/ ((pi/4)(R1^4-R2^4))

2. 120000000=((100*sinα))/(R1^2-R2^2)+ (100*cosα*R1 )/((pi/4)(R1^4-R2^4))

3. m=100(pi)(R1^2-R2^2 )(cosα)* R1

I know it looks like we have four unknowns with three equations, but I am going to assume the value of R1. Going forward, I will have the following unknowns:
α, R2, m

I tried solving this using Maple, but unfortunately all my values were 0. I am pretty sure I wrote it right. Otherwise, is there any other software I can use to solve this? Excel/Matlab?

If so, which functions should I use? Are there any constraints that I will have to define?

PS - I attached a picture of the formulas!

#### Attached Files:

• ###### calculation1.JPG
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2. Feb 12, 2014

### DrBwts

Solve (1) & (2) independently as you have 2 equations with 2 unknowns then substitute into (3)

As you know R1 & as long as R1 does NOT = R2 then I'd try multiplying (1) & (2) through by (pi/4)(R1^4-R2^4)

Last edited: Feb 12, 2014
3. Feb 13, 2014

### Lisa

If you wrote it like here, you made mistake. For what you use double quotes?

4. Feb 13, 2014