JEE Main 20188 April
- Exam
- JEE Main
- Year
- 2018
- Date
- 8 April
- Subject
- Mathematics
- Chapter
- Heights and Distances
JEE Main 2018 · 8 April · Mathematics · Heights and Distances
PQR is a triangular park with PQ = PR = 200m . A T.V. tower stands...
is a triangular park with . A T.V. tower stands at the mid-point of . If the angles of elevation of the top of the tower at and are respectively, and , then the height of the tower (in ) is:
Options
- A
- B
- C
- D
Correct answer
B.
Step-by-step solution
Let the height of the tower be
In
Now in
In a triangle sides opposite to equal angles are
equal∴ MN = PM = h∆ PMQPM = \sqrt{( 200{)}^{2} - ( \sqrt{3}h{)}^{2}}∴ From h = \sqrt{( 200{)}^{2} - ( \sqrt{3}h{)}^{2}}⇒ h = \sqrt{( 40000 ) - 3{h}^{2}}⇒ {h}^{2} = 40000 - 3{h}^{2}⇒ 4{h}^{2} = 40000⇒ {h}^{2} = 10000m⇒ h = 100m