Question

Mayank made a bird-bath for his garden in the shape of a cylinder with a hemispherical depression at one end as shown in the figure. The height of the cylinder is 1.45 m and its radius is 30 cm. Find the total surface area of the bird-bath. (Take π = 22/7)​

Answer 1

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Let h be the height of the cylinder and r be the common radius of the cylinder and hemisphere.

Then, the total surface area of the bird-bath

=CSA of cylinder + CSA of the hemisphere

= 2πrh + 2πr^2

= 2π r(h + r)

= 2 (22/7) × 30 × (145 + 30) cm^2

= 33000 cm^2

 = 3.3 m^2

Answer 2

Answer:

Let, 'r' be the common radius for both the hemisphere and cylinder. Then the height of the hallow cylinder be 'h'.

So, radius (r) = 30cm

Height (h) =1.45m➡️145/100m➡️145/100×100➡️145cm

the total surface area of the bird-bath = curved surface area of the hemisphere + curved surface area of the cylinder

$= > 2\pi \: r {}^{2} + 2\pi \: rh \\ = > 2\pi \: r(r + h ) \\ = > 2(22 \div 7)(30)(30 + 145) \\ = > 44 \div 7(30)(175) \\ = > 44(30)(25) \\ = > 33000cm {}^{2} \\ = > 33000 \div 100 \times 100m {}^{2} \\ = > 33000 \div 10000m {}^{2} \\ = > 3.3m {}^{2}$