Question

The length of the side of a square with an area of $1600m^2$ is ____.

• A. 80m
• B. 44m
• C. 30m
• D. 40m

Answer 1

The correct option is D 40m

If the side of square is a, its area is $a^2$.

According to question,

$a^2=1600$
$a^2=2\times 2\times 2\times 2\times 10\times 10$
$a=\sqrt{\underset{–}{2\times 2}\times \underset{–}{2\times 2}\times \underset{–}{10\times 10}}$
$\downarrow \downarrow \downarrow$
$\text{2}\times \text{2}\times \text{10}$
$a=40m$