Each side of a rectangular field is increased by 10%. Then the percentage increase in the area of the field is:

Let the length and breadth of the rectangular field are $$l$$ and $$b$$ respectively.

Area of the rectangular field = $$lb$$

Length after increase of 10% = $$\frac{110}{100}l$$

Breadth after increase of 10% = $$\frac{110}{100}b$$

Area after increase in length and breadth = $$\frac{110}{100}\times\frac{110}{100}lb$$ = $$\frac{121}{100}lb$$

$$\therefore\ $$Percentage increase in area of the field = $$\frac{\frac{121}{100}lb-lb}{lb}\times100\ $$ = $$\frac{\frac{21}{100}lb}{lb}\times100$$ = $$\frac{21}{100}\times100$$ = 21%

Hence, the correct answer is Option A