Write y' in explicit form

Question

cos y = x (Express y' explicitly)

Answer 1

cosy = x= x/1, siny = sqr(1-x^2)

-siny(y') = 1

y'(x) = 1/-siny = -1/sqr(1-x^2)

or

x=cosy

dx/dy =-siny

dy/dx = y' = -1/siny= -1/sqr(1-x^2)