# Math Help - Solve for theta

1. ## Solve for theta

25sin@ -1.5 cos@ = 20 @ = theta

2. Originally Posted by jewd777
25 sin@ -1.5 cos@ = 20, whats @ = ?
Hint: Apply the identity $A\cos\theta+B\sin\theta=\sqrt{A^2+B^2}\cos\!\left( x-\tan^{-1}\!\left(\tfrac{B}{A}\right)\right)$

3. there may be a more clever way but by brute force and ignorance:
Solve for 25 sin(@) = 20+1.5cos(@)

square both sides and convert the LHS to a fn of cos(@)

you now have a quadratic in cos@