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Given: Length of each side of cube = 5 cm Formula used: Surface area of the cuboid = 2(LB + BH + HL) Where, L = length of the cuboid B = breadth of the cuboid H = height of the cuboid Calculation: Now, 3 cubes are joined end to end The length of the resulting cuboid will be = 5 + 5 + 5 = 15 cm But, the breadth and height will remain the same. Breadth = 5 cm and Height = 5 cm Surface area of the cuboid = 2(LB + BH + HL) ⇒ Surface area of the cuboid = 2(15 × 5 + 5 × 5 + 5 × 15) = 2(75 + 25 + 75) ⇒ Surface area of the cuboid = 350 cm2 ∴ The surface area of the resulting solid is 350 cm2 India’s #1 Learning Platform Start Complete Exam Preparation
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A metallic right circular cone 20 cm high and whose vertical angle is 60° is cut into two parts at the middle of its height by a plane parallel to its base. If the frustum so obtained be drawn into a wire of diameter , find the length of the wire.
In fig. cone ABC is cut out by a plane parallel to the base FG. DEFG is the frustum so obtained. Let O be the centre of the base of the cone and O’ the centre of the base of the frustum. It is given that ∠BAC = 60° ∠OAC = 30° In right triangle AOC, tan And, C = Height of the frustum = P'O = volume of the frustum =
Radius of the wire = Let h be length of the wire Volume of wire = From (iii) and (iv), we get |