Answer :
x = sin(x + y)
differentiating term by term:-
1 = cos(x + y) * (1 + y')
1 = cos (x + y) + y' cos(x + y)
y' = 1 - cos(x + y)
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cos (x + y)
differentiating term by term:-
1 = cos(x + y) * (1 + y')
1 = cos (x + y) + y' cos(x + y)
y' = 1 - cos(x + y)
------------------
cos (x + y)