Answer:
The value of f is 4π.
Step-by-step explanation:
The given equation is

We need to find the value of f for the above equation.
Isolate f to solve the given equation.
Subtract 3π from both sides of the above equation.

On combining like terms we get


The value of f is 4π.
Substitute f=4π in the given equation to check the solution.



Therefore the solution is correct.