title: SymPy unable to solve a system of trigonometric equations
body: <p>I'm trying to get SymPy to solve a system of equations but it gives me an error saying: </p>
  
  <pre><code>NotImplementedError: could not solve 3*sin(3*t0/2)*tan(t0) + 2*cos(3*t0/2) - 4
  </code></pre>
  
  <p>Is there another way for me to be able to solve the system of equations:</p>
  
  <pre><code>sin(x)+(y-x)cos(x)           = 0
  
  -1.5(y-x)sin(1.5x)+cos(1.5x) = 2
  </code></pre>
  
  <p>I used :</p>
  
  <pre><code>from sympy import *
  solve([sin(x)+(y-x)cos(x), -1.5(y-x)sin(1.5x)+cos(1.5x)-2], x, y)
  </code></pre>