Question

When integrating with respect to y in order to find the area between two curves, how do you know which function is f(y) and g(y) when the area equals the definite integral of f(y)-g(y)?

Answer 1

In other words, how do you know which of the two functions is being subtracted from the other when integrating with respect to y?

Answer 2

When you integrate WRT x, the UPPER(larger) function is your f(x).
You subtract the lower from the upper function.


When you integrate WRT y, the RIGHTMOST(larger) function is your f(y).
You subtract the left from the right function.