Question

    The sum of length, breadth and height of cuboid is 20cm.If the length of the diagonal is 12 cm, then find the total surface area of the cuboid( in cm 2 )

    A 256 Correct Answer Incorrect Answer
    B 225 Correct Answer Incorrect Answer
    C 196 Correct Answer Incorrect Answer
    D 64 Correct Answer Incorrect Answer

    Solution

    l+ b+ h = 20 Diagonal =12 Diagonal = √ l2+b2+h2 (l+ b+ h)2 = l2+b2+h2+ 2(l b+ b h +h l) (20)2 = (12)2 +2(l b+ b h +h l) 400 = 144 +2(l b+ b h +h l) 2(l b+ b h +h l) = 400-144=256 Total surface area of cuboid =256

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