Question

Find the perimeter of a rectangle whose length is $40$cm and the length of one of the diagonal is $41$cm

Answer 1

Now in $DABC,AB\perp BC$

$\therefore {AB}^2+{BC}^2={AC}^2$

$\Rightarrow {AB}^2+{40}^2={41}^2$

$\Rightarrow {AB}^2=1681-1601=81$

$\Rightarrow AB=9$

$\therefore$Perimeter$=2(AB+BC)=2(9+40)=2\times 49=98$cm