Recall also that the area of the shaded region is given by:
From the fundamental Theorem of Calculus, f(x)- g(x) can be re-written as:
Where y (the variable of integration) could be any other variable apart from x.
Now putting (2) in (1) gives:
The above double integral gives the area of the shaded region.
Find to 4 decimal places the area of the path of the surface