Question

Find the diagonal of a square whose side is $10cm$

Answer 1

The side of square is $10cm$
In right angled $△ABD$
$A{B}^2+A{D}^2=B{D}^2$ [according to Pythagoras theorem]
$(10{)}^2+(10{)}^2=B{D}^2$$
$100+100=B{D}^2$
$B{D}^2=200$
$BD=10\sqrt{2}cm$
$\therefore$ Diagonal of square $=10\sqrt{2}cm$.