## Thomas' Calculus 13th Edition

$y'=(-2-cscθ-\frac{θ^2}{2})\times(\frac{cscθcotθ}{2}-θ/2)$
Take the derivative of the equation using Trigonometric Derivatives and Power Rule. Then apply Chain Rule to the inner terms: $y'=2(-1-\frac{cscθ}{2}-\frac{θ^2}{4})\times(0+\frac{cscθcotθ}{2}-\frac{2θ}{4})$ $=(-2-cscθ-\frac{θ^2}{2})\times(\frac{cscθcotθ}{2}-θ/2)$