There is a flag-post on the top of a 10m high tower. from a point on the ground, the angle of elevation of the top of the flag-post is 60 .find the height of the flag-post
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Answered by
1
Answer:
Let A be the point of observation and B be the foot of the building.
Let BC denote the height of the building and CD denote height of the flag post.
Given that ∠CAB=45
∘
,∠DAB=60
∘
and CD=10m
Let BC=h metres and AB=x metres.
Now, in the right angled △CAB,
tan45
∘
=
AB
BC
.
Thus, AB=BC i.e., x=h (1)
Also, in the right angled △DAB,
tan60
∘
=
AB
BD
⇒AB=
tan60
∘
h+10
⇒x=
3
h+10
(2)
From (1) and (2), we get h=
3
h+10
⇒
3
h−h=10
⇒h=(
3
−1
10
)(
3
+1
3
+1
)=
3−1
10(
3
+1)
=5(2.732)=13.66m
Hence, the height of the building is 13.66m.
Answered by
0
The answer to this question is:
Step-by-step explanation:
60÷10
=6
so,the answer is 6
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