Q.

The Atal Tunnel, also known as the Rohtang Tunnel, is a highway tunnel built under the Rohtang Pass in the eastern Pir Panjal range of the Himalayas, located on the Leh–Manali highway in Himachal Pradesh. Spanning a length of 9.02 km, it is the world’s longest tunnel situated above 10,000 feet and is named after the former Prime Minister of India, Atal Bihari Vajpayee. The cross-section of a tunnel is shown in figure. The radius of circular part is 5 square root of 2 space end root m e t r e s space a n d angle A O B equals 90 degree.

Based on the above information, answer the following questions:

 

(iii) (b) What is the area of cross-section of the tunnel

1 70π2+25 m2  
2 75π2+25 m2  
3 75π2+20 m2  
4 75π2+19 m2  

Ans.

(2)

Area of cross-section of the tunnel

=270°360°×πr2+arAOB

=34πr2+12×OA×OB

=34π(52)2+12×52×52

=75π2+25 m2