Question

The sum of length, breadth and height of a cuboid is 21 cm and the length of its diagonal is 12 cm. Find the surface area of the cuboid?

Answer 1

Answer:

293 cm^2

Step-by-step explanation:

length + breadth + height = 21

diagonal=

$\sqrt{ {l}^{2} + {b}^{2} + {h}^{2} } = 21$

${l}^{2} + {b}^{2} + {h}^{2} = 144$

${l}^{2} + {b}^{2} + {h}^{2} + 2(lb + bh + hl) \\ - 2(lb + bh + hl) = 144$

${(l + b + h)}^{2} - 2(lb + bh + hl) = 144$

${(21)}^{2} - 2(lb + bh + hl) = 144$

$2(lb + bh + hl) = 441 - 144$

Surface area = 293 cm^2