If $\rm \frac{x}{\cos \theta}=\frac{y}{\cos \left(\frac{2\pi}{3}-\theta\right)}=\frac{z}{\cos\left(\frac{2\pi}{3}+\theta\right)}$ then what is x + y + z equal to? 

If p tan (θ - 30°) = q tan (θ + 120°), then what is (p + q) / (p - q) equal to?

What is the maximum value of a cos x + b sin x + c? 

$$ \text { What is } \frac{\sqrt{3} \cos 10^{\circ}-\sin 10^{\circ}}{\sin 25^{\circ} \cos 25^{\circ}} \text { equal to ? } $$