Question

17. Two walls of a house have windows one each of
the shape of a rectangle, having a semicircle on
the top. The rectangular part is 1.2 m long and
42 cm wide. From how much area the air can
come in the room?​

Answer 1

The total air incoming area is 11466 cm².

• Given data :

Number of windows = 2

Length of the window = 1.2 metres = 120 centimetres [Term of unit conversion is 100 centimetres = 1 metres]

Width of the window is 42 centimetres.

• Now, the diameter of the above semicircle = width of window

• So,the width of the semicircle part = 1/2 × width of the window

= 1/2 × 42

= 21 centimetres

• Now,the area of the semicircle part will be :

= {π × (21)²}/2

= (22/7 × 441)/2

= 693 cm²

• Now,the area of rectangular part

= (120×42)

= 5040 cm²

• So,the total area of a window

= (5040+693)

= 5733 cm²

• So,the total area of two windows

= 5733×2

= 11466 cm²

So,the total area of two windows = area of air incoming = 11466 cm² (answer)