# From a point 100

The figure for the question is

Let A be the point 100 m above lake and C be the helicopter and C' be the reflection of helicopter in water.

Given,

Angle of elevation of helicopter from point A, ∠CAQ = 30° [Let θ1]

Angle of depression of reflection from point A, ∠QAC' = 60° [Let θ2]

Also,

AB = PQ = 100 m …[1]

AQ = BP …[2]

CP = CP' [image distance is equal to object distance]

And let CQ = 'x'

CP = CQ + PQ = 100 + x

⇒ CP' = 100 + x …[3]

In ΔACQ

From [2]

⇒ BP = x√3 m …[4]

In ΔAQC'

[From [3]]

3x = x + 200

⇒ 2x = 200

⇒ x = 100 m

And

Height of helicopter above lake = CP = x + 100

= 100 + 100 = 200 m

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses
RELATED QUESTIONS :

At a point A, 20 Mathematics - Board Papers

If <img style="veRD Sharma - Mathematics

From a point on tMathematics - Board Papers

Evaluate each of RD Sharma - Mathematics

Express <imRD Sharma - Mathematics