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:

 

(ii) Find the height of the tunnel.

1 5(2+3) m  
2 4(2+1) m  
3 5(2+1) m  
4 5(-2+1) m  

Ans.

(3)

The height of the tunnel will be (OM+OC). In∆OAM and∆OBM

∠OAM=∠OBM(∵OA=OB)∠OMA=∠OMB=90°

By AA similarity,∆OAM~∆OBMAM=MB=AB2=5 m

In right ∆OMB:OB2=OM2+MB2

52)2=OM2+(5)250=OM2+25OM=5 m

OC=OA=52m∴ Height of the tunnel =OM+OC=5(2+1) m