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The length, breadth, and height of a rectangular solid are in the ratio 5: 4: 2. If the total surface area is 1216 cm2, find the length, the breadth, and the height of the solid. - Mathematics

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प्रश्न

The length, breadth, and height of a rectangular solid are in the ratio 5: 4: 2. If the total surface area is 1216 cm2, find the length, the breadth, and the height of the solid.

योग

उत्तर

The rectangular solid is a cuboid.

Let the length of the cuboid = 5a, breadth = 4a, and height = 2a

Total surface area of a cuboid of length l, breadth b and height h = 2(l × b + b × h + l × h)

Given,

Total surface area of the cuboid = 1216 cm2
⇒ 2(5a × 4a + 4a × 2a + 2a × 5a) = 1216 cm2
⇒ 76a2 = 1216
⇒ a = 4.

Hence, the length of the cuboid = 5a = 20 cm, breadth = 4a = 16 cm, height = 2a = 8 cm.

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अध्याय 21: Solids [Surface Area and Volume of 3-D Solids] - Exercise 21 (A) [पृष्ठ २६९]

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सेलिना Concise Mathematics [English] Class 9 ICSE
अध्याय 21 Solids [Surface Area and Volume of 3-D Solids]
Exercise 21 (A) | Q 1 | पृष्ठ २६९

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