The angle of elevation of the top of a vertical tower from a point on the ground is 60 degree. From another point 10m vertically above the first, its angle of elevation is 45 degree. Find the height of the tower.
Answers
let dist. between base of tower and obs. pt. = y
at first angle it makes with ground = 60 degree
tan(60) = sqrt{3} = (x + 10)/y . . . . . . (eq 1)
next angle = 45 degree
pt is 10 m above the ground
tan(45)= 1 = x/y
:. x=y . . . . . . . . . (eq. 2)
substituting value of y in eq. 1
x + 10 = 1.732 x
:. x = 13.66 m
Answer:
23.66m
Step - by - Step explanation:
Also according to the question the diagram can be drawn as in the pic.
So let height of the tower be EC
Also let the angle EAD be 45° and the angle EBC be 60°
Let ED be x and in the rectangle ABCD we know that AB = CD = 10
and BC = AD
Since we don't need hypotenuse value let's apply tan or cot.
( for easy simplification I am applying tan )
So, in triangle AED ,,,
Tan 45 ° = ED/AD = ED/BC = x / BC
1 = x/BC
x = BC ----------------------------(1)
In triangle EBC ,,,
Tan 60 ° = EC/BC
√3 = x + 10 / BC
BC(√3) = x + 10
x√3 - x = 10
x ( √3 - 1) = 10
x = 10 / ( √3 - 1 )--------------------------(2)
According to the pic we can say that height of the tower is EC = ED + DC
= x + 10
= [10/(√3-1)] +
10
= (10+10√3-
10)/(√3-1)
= 10√3/(√3-1)
If we substitute √3 = 1.732
We get height if the tower as 23.66 m
Thanks
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