Multiple choice

The length of a diagonal of a cuboid is 11 cm. The surface area is 240 square cm. What is the sum of its length, breadth and height?

  1. 16 cm

  2. 17 cm

  3. 18 cm

  4. 19 cm
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Diagonal d = sqrt(l^2 + w^2 + h^2) = 11, so l^2 + w^2 + h^2 = 121. Surface area = 2(lw + wh + hl) = 240, so lw + wh + hl = 120. (l+w+h)^2 = l^2 + w^2 + h^2 + 2(lw + wh + hl) = 121 + 240 = 361. l+w+h = sqrt(361) = 19.

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