Question

How does a double integral gives area ? I cannot imagine it

Answer 1

In general, double integrals calculate volume (or can be interpreted as such).

That is:


`\displaystyle \iint_(A) f(x,t)dA`

gives the net volume under the function
`f(x,y)` and the x-axis.

However, if
`f(x,y)=1`, then the height of the solid is 1 and its volume is equivalent to its base area.