Is this trigonometric solution correct?

[mileena]

Homework Statement

Solve for y':

4[(cos x)(cos y)(y') + (sin y)(-sin x)] = 0

Homework Equations

none

The Attempt at a Solution

4[(cos x)(cos y)(y') + (sin y)(-sin x)] = 0

4y' (cos x) (cos y) - 4 (sin x) (sin y) = 0

4y' (cos x) (cos y) = 4 (sin x) (sin y)

y' = [4 (sin x) (sin y)] / [4 (cos x) (cos y)]

y' = (sin x sin y) / (cos x cos y)


Thanks! I am really shaky at trigonometry, so the above worries me.

 

[rock.freak667]

Yes that is correct. If you want to, you can simplify it even more using the fact that sinA/cosA = tanA.

 

[mileena]

Thanks rock.freak667! See what I mean? I didn't even see that in the equation, although I do know that tan x = sin x/cos x.