Differentiate both sides of the equation.
Differentiate using the Power Rule which states that is where .
Differentiate using the chain rule, which states that is where and .
To apply the Chain Rule, set as .
The derivative of with respect to is .
Replace all occurrences of with .
Rewrite as .
Reform the equation by setting the left side equal to the right side.
Rewrite the equation as .
Divide each term by and simplify.
Divide each term in by .
Simplify the left side of the equation by multiplying out all the terms.
Dividing two negative values results in a positive value.
Cancel the common factor of .
Cancel the common factor.
Divide by .
Simplify .
Cancel the common factor of and .
Rewrite as .
Move the negative in front of the fraction.
Convert from to .
Replace with .
Find dy/dx x=cos(y)