I solved a partial derivative problem and have the correct answer but the book I am using, Courant's Differential and Integral Calculus, has the answer in algebraic rather than trigonometric form. I never really worked on learning the translation of trig equations to algebraic form (except in the most basic cases). Anyway, my answer is in the form:
I'd appreciate if someone could show me the translation presumably using right triangles and also perhaps suggest a good book or resource to work out similar problems. I need to bone up on this aspect of trig.
Thanks in advance