Question

Mayank made a bird-bath for his garden in the shape of a cylinder with a hemispherical depression at one end (see fig. 13.9). 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 = 22 7 )

Answer 1

Answer:

height of cylinder=1.45m

radius of cylinder=30/100=3/10cm

Total surface area =2πrh+2πr^2

= 2πr(r+h)

= 2×22/7×3/ 10 (3/10+1.45)

=44/7×3/10×(3/10+145/100)

=44/7×3/10×175/100

=>33/10= 3.3

Answer 2

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

Total, surface area of bird- bath

= CSA of cylinder + CSA of hemisphere

$\bf = 2πrh +2πr² \\ \\ \bf </p><p>= 2πrh+2πr²=2πr(r+h) \\ \\ \bf </p><p>= 2× \frac {22}{7} ×30(145+30) cm²</p><p>\\ \\ \bf =33000cm² \\ \\ \bf 3.3m²$