## Answer :

breadth = b

height = h

but here we have l+b+h = 19 cm

and for diagonal = 11

like this,

**∴**√ l^2 + b^1 + h^2 = 11

**∴**l^2 + b^1 + h^2 = 121

so,

[ l + b + h ]^2 = l^2 + b^1 + h^2 + 2[lb + bh + lh]

**∴**19 ^2

**=**121 + 2[lb + bh + lh]

**∴**361 - 121= 2[lb + bh + lh]

**∴**240

**=**2[lb + bh + lh]

∴ surface area of cuboid box is 240 cm^2