Exercise 36 Page 9

First, let's recall that π is a constant, not a variable. Keeping this in mind, we can solve the given equation for f by subtracting 3π from both sides of the equation. We want to subtract 3π because addition and subtraction are inverse operations — they cancel each other out. This is allowed by the Subtraction Property of Equality.

We will check our solution by substituting this result back into the original equation and simplifying. If doing so results in an identity, our solution is correct.

Since substituting f=4π resulted in an identity, our solution is correct.