We have,
r = radius of the cylinder
= radius of hemispherical ends = 14 cm
h = height of cylinder = 72 cm
∴ Total surface area = curved surface area of the cylinder + surface areas of hemispherical ends
= (2rh +2 x 2r²) cm²
= 2r (h + 2r) cm²

Now, cost of polishing the surface of the solid at the rate of 5 paise per sq. m

Let r cm be the radius, h cm be the height of the cylinder then
r = 3.5 cm
and    h = 20 cm.
Let r₁ be the radius of the hemisphere, then
r₁ = 3.5 cm
Now,
Total surface area of the area of the article
= curved surface area of the cylinder
+ 2 (curved surface area of hemisphere)
= 2πrh + 2 (2 πr₁²)
= 2 πrh + 4 πr²    [∵ r = r₁]
= 2 π r(h + 2r)

Let the side (edge) of the cube be a cm, then a
= 5 cm.
Let radius of the hemisphere be r, then
r = 2.1 cm
Now,
The total surface area of the block
= T.S.A of cube - base area of hemisphere + C.S.A of hemisphere
= 6 (side)² – r² + 2r²
= 150 – r² + 2 r²
= 150 + ²

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We have, r₁ = Radius of the base of the cylinder = 7m
r₂ = Radius of the base of the cone = 7 m
h₁ = Height of the cylinder = 6m



In right triangle EOC, we have

Thus, slant height (CE) = 14 m
Now,Surface area of building = Curved surface area of cylinder + curved surface area of cone

Cost of painting the building from inside at the rate of Rs. 30/m²
= Rs. (572 x 30) = Rs. 17160.  

Let r cm be the radius and h cm the height of the cone, then r = 7 cm, and h = 24 cm. Let l cm be the slant height of am cone, then

Let r₁ cm be the radius of hemisphere then
r₁ = 7 cm
Now, Total surface area of toy
= C.S.A of cone + C.S.A. of hemisphere

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