# Find the Derivative f(x)=2cos(2y)

The function declaration varies according to , but the input function only contains the variable . Assume .
Since is constant with respect to , the derivative of with respect to is .
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 .
Differentiate.
Multiply by .
Since is constant with respect to , the derivative of with respect to is .
Multiply by .
Differentiate using the Power Rule which states that is where .
Multiply by .
Find the Derivative f(x)=2cos(2y)