Finding the derivative of implicit function y = y (x) determined by e ^ y = cos (x + y)

Finding the derivative of implicit function y = y (x) determined by e ^ y = cos (x + y)

e^y=cos(x+y)
(e^y).y' = -sin(x+y) .( 1+ y')
(e^y + sin(x+y) ) y' = -sin(x+y)
y' =-sin(x+y)/(e^y + sin(x+y) )