thsym = sym.pi*7/6
theta = float(thsym)
# plot the unit circle
x = np.linspace(0,2*np.pi,200)
plt.plot(np.cos(x),np.sin(x),color='gray')
plt.plot([-1.1,1.1],[0,0],'--',color='gray')
plt.plot([0,0],[-1.1,1.1],'--',color='gray')
plt.plot(np.cos(np.linspace(0,theta)),np.sin(np.linspace(0,theta)),'k',linewidth=3)
plt.plot([0,np.cos(theta)],[0,np.sin(theta)],'k:')
plt.plot(np.cos(theta),np.sin(theta),'ko')
plt.plot([0,0],[0,np.sin(theta)],'r',label='sin')
plt.plot([0,np.cos(theta)],[np.sin(theta),np.sin(theta)],'r:')
plt.plot([0,np.cos(theta)],[0,0],'b',label='cos')
plt.plot([np.cos(theta),np.cos(theta)],[0,np.sin(theta)],'b:')
plt.title('$\\theta = %s$' %sym.latex(thsym))
plt.gca().set_aspect('equal')
plt.legend()
plt.show()