Q4 of 48 Page 261

Chirag made a bird - bath for his garden in the shape of a cylinder with a hemispherical depression at one end, (see the figure 14.11). The height of the cylinder is 1.5 m and its radius is 50 cm. Find the total area of the bird - bath. (π = 3.14)

Given.


A vessel is made by depressing hemisphere on cylinder


The radius of the hemisphere is 50 cm


Height of the cylinder is 150 cm


Formula used/Theory.


Curve surface area of Cylinder = 2πrh


Curve surface area of Hemisphere = 2πr2


⇒ As we put hemisphere in Cylinder


∴ Area of bird - bath is sum of CSA of both hemisphere and cylinder


Area of Bird - bath = CSA of cylinder + CSA of Hemisphere


= 2πrh + 2πr2


= 2πr[h + r]


TSA of toy = 2 × 3.14 × 50 × [150 + 50]


= 2 × 3.14 × 50 × [200]


= 62800 cm2


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