Question

please explain the answer​

Answer 1

Question

A 2 unit high marble slab with 1 unit × 4 unit base is fixed to the floor of a courtyard. The surface area of marble which is visible is

Answer

24 sq units

Explanation

Here, h = 2 units

l = 1 units

b = 4 units

We are asked for the area of marble which is visible.

Since the marble is fixed to the floor, the base of marble won't be visible. Therefore, it's only the top and the 4 lateral surfaces that are visible.

Hence, required area = lateral surface area + area of top

Lateral surface area = 2(l + b)h

area of top = l × b

⇒ required area = 2(1 + 4)2 + 1 × 4

⇒ 2(5)2 + 4

⇒ (10)2 + 4

⇒ 20 + 4

⇒ 24 unit sq.

Answer 2

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