The angle of elevation of the top of a tower at a point on the ground level is 30 degree .After walking a distance of 100mts towards the foot of the tower along the horizontal line through the foot of the tower is 60degree.Find the height of the tower?

Asked by Bholanath Beura | 24th Oct, 2012, 08:28: PM

Expert Answer:

Answer : Let AB be the ht of the tower as h m , and BD be the original distance making and elevation of 30 degrees with angle ADB abd distance from the foot of tower = 100+x m  
and similarily , next elevation from distance x m making 60 degrees by angle ACB.
 
In triangle ABD, 
=> AB/BD= tan 30
=> h/(x+100) = 3-1/2 ..................(1)
 
In triangle ABC, 
=> AB/BC= tan 60
=> h/x = 31/2 ..................(2)
dividing eq 1 and 2 , we get
 
=> x/ (x+100) = 1/3 
=> 3x = x+ 100 {cross multiplication}
=> 2x = 100 
=> x = 50 m 
 
using the value of x in eq 2 we  get 
=> h/50 = 31/2
=> h= 50*31/2 = 86.60 m (approx) is the required height of the tower Answer 

Answered by  | 25th Oct, 2012, 03:19: PM

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