Diagram must be included With explanation!
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Question is very simple
Answers
EXPLANATION.
Person walking along a straight road.
A hill observed at two points distance = √3 km.
The angle of elevation of the hill to be 30° and 60°.
As we know that,
Formula of :
⇒ tanθ = Perpendicular/Base.
⇒ tan30° = 1/√3.
⇒ tan60° = √3.
⇒ BC = Height.
⇒ AC = Base. = √3 + x.
In ΔBDC.
tan60° = h/x.
⇒ √3 = h/x.
⇒ h = √3x. - - - - - (1).
In ΔBAC.
⇒ tan30° = h/√3 + x.
⇒ 1/√3 = h/√3 + x.
Put the value of h = √3x in the equation, we get.
⇒ 1/√3 = √3x/√3 + x.
⇒ 3x = √3 + x.
⇒ 2x = √3.
⇒ x = √3/2. - - - - - (2).
Put the value of x = √3/2 in the equation (1), we get.
⇒ h = √3x.
⇒ h = √3 (√3/2).
⇒ h = 3/2 km.
Option [A] is correct answer.
Answer:
Answer :-
- The height of the hill is (3/2)km.
Solutions :-
Hey mate,
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In the question given that,(A person walking along a straight road towards hill observes at two point distance root 3km.The angle of elevation of hill is to be 30degree and 60degree .)
So,
- tan theta = opp/adj
- tan 30degree = 1/root3
- tan 60degree = root 3.
And ,
- Here BC is height and AC is base i.e root 3 +x.
Consider ,Triangle BDC
- tan 60degree = opp/adj
- tan 60degree = (h/x)
- root 3 =( h/x)
- h = root3 × (x) (i)
And also ,Consider Triangle BAC
- tan 30degree =opp/adj
- tan 30degree =h/root 3 +(x)
- 1/(root 3)=root 3 x/root 3+(x)
- 3x = root 3+(x)
- 3x-x = root 3
- 2x =root 3
- x =root 3/2. (ii)
- h = root 3×(x)
- h = root 3 × root 3/2
- h =(3/2)km.
Therefore,