Question

Multiple integrals and area of regions.​

Answer 1

Answer:

We can do the same trick for double integrals. The integral of a function f(x,y) over a region D can be interpreted as the volume under the surface z=f(x,y) over the region D. ... But the integral of f(x,y)=1 is also the area of the region D. This can be a nifty way of calculating the area of the region D.