Question

The length of diagonal of a square is $5\sqrt{2}$. Then its perimeter is ___.

• A. $5$
• B. $50$
• C. $20$
• D. $100$

Answer 1

The correct option is C $20$

Let the side be $a$

$a^2+a^2=(5\sqrt{2}{)}^2$

$2a^2=50$

$a^2=25$

$a=5$

Perimeter $=4a=4\times 5=20$