There are two vessels in the sea, opposite side of a lighthouse. The angle of elevation of the top of the lighthouse is observed from the vessel is 30° and 45°, respectively. Then, what is the distance between the two vessel, if the lighthouse is 120 m high?
There are two vessels in the sea, opposite side of a lighthouse. The angle of elevation of the top of the lighthouse is observed from the vessel is 30° and 45°, respectively. Then, what is the distance between the two vessel, if the lighthouse is 120 m high? Correct Answer 120(1 + √3) m
Given:
Height of lighthouse = 120 m
Formula Used:
Calculation:
[ alt="F53 Harshit 12-5-2021 Swati D4" src="//storage.googleapis.com/tb-img/production/21/05/F53_Harshit_12-5-2021_Swati_D4.png" style="width: 235px; height: 180px;">
With help of the data given in the question, above diagram can be represented.
Suppose AB is the height of the lighthouse.
In ΔABC, ∠ACB = ∠CBA = 45°
∴ CA = AB = 120 m
In ΔABD, ∠ADB = 30°
⇒ tan30° = AB/AD
⇒ 1/√3 = 120/AD
⇒ AD = 120√3
∴The distance between two vessels (CD) = AC + AD = 120 + 120√3
⇒ 120(1 + √3) m