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## Main Question or Discussion Point

Hi y'all.

Here is exactly what is stated on the theory page of my book:

The

Area of R= ∫∫dR

The

Mass of R= ∫∫ρdR

I'm not at all understanding this first part of the theory, why is it that the area of the region R in the xy-plane is the case f(x,y)=1 and how did they obtain that express for the area R?

All help is immensely appreciated as I'm tearing my hair out over this.

Thanks!

Here is exactly what is stated on the theory page of my book:

**Example: Area of a Region**The

*area of a region R in the xy-plane*corresponds to the case where*f(x,y)=1*.Area of R= ∫∫dR

**Example: Mass of a Region**The

*mass of a region R in the xy-plane*with mass density per unit area ρ(x,y) is given by:Mass of R= ∫∫ρdR

I'm not at all understanding this first part of the theory, why is it that the area of the region R in the xy-plane is the case f(x,y)=1 and how did they obtain that express for the area R?

All help is immensely appreciated as I'm tearing my hair out over this.

Thanks!