Solving 2 non linear equations with 2 unknown

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These are 2 Law of Cosines equation, i need your help to solve this:

(r1+150)^2 = (r1+200)^2 + 499.1^2 -2*(r1+200) * 499.1 * cos(16.177 )

r1^2 = (r1+200)^2 + 1267.9^2 -2*(r1+200) * 1267.9* cos (teta - 16.177 )


Unknowns: r1, teta

please help me solve this using matlab!!!

Thanks

Tyler
0
Reply ronshinyo (2) 5/23/2010 6:39:08 AM

tyler wrote:
> These are 2 Law of Cosines equation, i need your help to solve this:
> 
> (r1+150)^2 = (r1+200)^2 + 499.1^2 -2*(r1+200) * 499.1 * cos(16.177 )
> 
> r1^2 = (r1+200)^2 + 1267.9^2 -2*(r1+200) * 1267.9* cos (teta - 16.177 )
> 
> 
> Unknowns: r1, teta
> 
> please help me solve this using matlab!!!

Expand the first equation in r1, and move everything to the same side. 
You will be left with a quadratic equation independent of theta, which 
you can solve directly using the usual formula. Substitute each of the 
two roots into the second equation and isolate down to 
cos(theta-16.177), take the arccos and add 16.177 to get the relevant 
theta. No Law of Cosines needed.

Caution: be sure you know whether you are talking about 16 1/6 degrees 
or 16 1/6 radians.
0
Reply Walter 5/23/2010 3:09:44 PM


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