a man standing at 72m distance observe the angle of elevation of the vertical tower.he know that the angle is cosine 0.53. find the height of the tower.

2
and one more is
Vertical tower is 20 m high. A man standing at some distance from the tower knows that the cosine of the angle of elevation of the top of the tower is 0.53. How far is he standing from the foot of the tower ?
u already said the distance as 72m
The question is itself a question

Answers

2014-10-05T12:30:10+05:30
We have, cos θ = 0.53, let distance of the man from the foot of the tower be x. 
AB = 20m, BC = x, then AC = √[x2 + (20)2] = √[x2 + 400] 
cos θ = BC/AC = x/√[x2 + 400] 
Or, 0.53 = x/√[x2 + 400] 
Or, (0.53)2 = x2/[x2 + 400] [Squaring both sides] 
Or, 0.2809 = x2/[x2 + 400] 
Or, x2 = 0.2809x2 + 112.36 
Or, x2 – 0.2809x2 = 112.36 
Or, 0.7191x2 = 112.36 
Or, x2 = 112.36/0.7191 = 12.5 m [Ans.]



                 
     
1 5 1
The Brainliest Answer!
2014-10-05T12:42:20+05:30

This Is a Certified Answer

×
Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
1.distance = 72m
   let height = h
cos α = 0.53
sin α = √1-0.53² = 0.848
tan α = sinα/cosα = 1.6
tanα = h/72
h = 72×1.6=115.2m

2.h = 20
 cos α = 0.53
distance from tower = d
tan α = 20/d
⇒d = 20/tan α = 20/1.6 = 12.5m
1 5 1
Thank you Sourav.
ur is right but method is wrong if u want u can check on google book
i have used trigonometry. What is wrong in it?
it is not wrong but this method is also right