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# code for solution of 2 algebraic equations

Posted 11 years ago
 hello dearsi am new to the mathematica forum as well as to using mathematica.i am a phd student and have developed a mathematical model, now needing the help of you guys in finding a solution2cos ?1 - 1.5sin ?1 = 0.08 ( (cos ?2)^2 )- 0.08( (sin ?2)^2 )+(.05)/?1 (cos ( ?1/2))     (1)2sin ?1 + 1.5cos ?1 = 2(0.08 cos ?2 sin ?2)+ sin(?1/2)                                   (2)This is a set of 2 equations with two unknowns, ?1 and ?2.If somebody can help me to solve this seemingly easy system but i have unsuccessfully tried a lot.Thanksif any body can help me
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Posted 10 years ago
 Hi everyone, I am trying to solve 4 coupled algepraic equations...but seems like sth is wrong ... I wrote a code with Solve function but Mathematica seems like running but not getting the solution! I have 4 unknowns (k1,eps1,k2 and k12 other than these 4 are constant numbers) and 4 equations.. Thanks for any help! The code is: Solve[{((-Cmu*k1^2/eps1)^2*S^2) + (x12/taux12)*(-2*k1 + k12) - eps1 == 0, -Ceps2*eps1^2/k1 - Ceps1*2*S*k1 + 2*(Cmu*k1^2/eps1)^2*S^2 + Ceps3*(eps1/k1)*(x12/taux12)*(-2*k1 + k12) == 0, -1/taux12*(-2*k2 + k12) + (e^2 - 1)* k2/(3*dp*(Sqrt[2*Pi/3*k2])/(24*alpha2*g0)) == 0, -1/taux12*((1 + x12)*k12 - 2*x12*k2 - 2*k1) - k12/(Cmu* k1/eps1/Sqrt[ 1 + 0.45*(3*Ur^2/2*k1)]) - ((k12*(Cmu* k1/eps1/Sqrt[1 + 0.45*(3*Ur^2/2*k1)])*S^2)/3) == 0}, {k1, eps1, k2, k12}, Cubics -> False, Quartics -> False] 
Posted 11 years ago
 Hello Mr. Chip Hurstactually, the angles theta 1 and theta 2 written above are functions of time t.and i need to solve them as function of time for onward plotting. i hope, you will keep on trying to find out any way for this issue.thanks anyway.
Posted 11 years ago
 Regardless of whether these are functions of time or not, the plot suggests choosing any value for ?1 and ?2 will not satisfy the system.i.e. suppose for t = 1, ?1[1] = x and ?2[1] = y, then the plot suggests f[x, y] == g[x, y] == 0is not satisfied.
Posted 11 years ago
 I don't think this system has a solution (over the reals). If we definef[?_, ?_] := 2 Cos[?] - 1.5 Sin[?] - 0.08 Cos[?]^2 + 0.08 Sin[?]^2 - 0.05 Cos[?/2]/?g[?_, ?_] := 2 Sin[?] + 1.5 Cos[?] - 0.16 Cos[?] Sin[?] - Sin[?/2]then we'd like to know where f[?, ?] == g[?, ?] == 0If we plot all three functions, it appears they don't simultaneously intersect.Plot3D[{f[x, y], g[x, y], 0}, {x, -10, 10}, {y, -10, 10}]
Posted 11 years ago
 The first step is to write both equations in Mathematica's syntax. For example:2sin ?1+1.5cos ?1=2(.08cos ?2 sin ?2)+ sin(?1/2)Should be:2 Sin[theta1]+ 1.5 Cos[theta1] == 2(0.08 Cos[theta2] Sin[theta2])+Sin[theta1/2] If you are new to using Mathematica, you will want a general overview before using it. Please see the Mathematica Virtual Book for an introduction to the correct syntax.Once you have both equations written out, you can try giving it to a function such as Solve or NSolve.