Non linear simultaneous equation

0.5*1.225*11.05^2*.71*2*(0+0.103*(0.169-Sigma)+(-.105)*deltaR)+0.44*.873*cos(Sigma)==0; 

0.5*1.225*1.87^2*.2574*0.8-0.5*1.225*11.05^2*0.71*(0+(-.34)*(0.169-Sigma)+0.21*deltaR)==0;

[MD Farmuzul Islam]

Thanks man. These are some output of an Radio controoled aircraft. i was wondering why i am getting this warning ?

Warning: Unable to solve symbolically. Returning a numeric solution using vpasolve.

> In sym/solve (line 304)

In answers (line 4)

[Star Strider]

As always, my pleasure!

The likely reason that a symbolic solution does not exist is that ‘Sigma’ is also the argument of the cos function, and inverting it (in this instance) to get a symbolic result is not possible.

The plot is not at all interesting:

[S,D] = ndgrid(-2*pi:0.1:2*pi, -1:0.1:1);
Eq1 = @(Sigma,deltaR) 0.5*1.225*11.05^2*.71*2*(0+0.103*(0.169-Sigma)+(-.105)*deltaR)+0.44*.873*cos(Sigma); 
Eq2 = @(Sigma,deltaR) 0.5*1.225*1.87^2*.2574*0.8-0.5*1.225*11.05^2*0.71*(0+(-.34)*(0.169-Sigma)+0.21*deltaR);

figure
mesh(S,D,Eq1(S,D))
hold on
mesh(S,D,Eq2(S,D))
hold off
grid on

[MD Farmuzul Islam]

Again, I really appreciate for your time.

[Star Strider]

As always, my pleasure!

Answer 1

[Star Strider]

I am not sure what you want to do with them.

Solving them is straightforward:

syms Sigma deltaR 
Eqns = [0.5*1.225*11.05^2*.71*2*(0+0.103*(0.169-Sigma)+(-.105)*deltaR)+0.44*.873*cos(Sigma)==0; 
0.5*1.225*1.87^2*.2574*0.8-0.5*1.225*11.05^2*0.71*(0+(-.34)*(0.169-Sigma)+0.21*deltaR)==0;];

S = solve(Eqns)
Sigma = S.Sigma
deltaR = S.deltaR