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Aptitude - Height and Distance - Discussion

Discussion Forum : Height and Distance - General Questions (Q.No. 1)
Height and Distance
1.
Two ships are sailing in the sea on the two sides of a lighthouse. The angle of elevation of the top of the lighthouse is observed from the ships are 30° and 45° respectively. If the lighthouse is 100 m high, the distance between the two ships is:
173 m
200 m
273 m
300 m
Answer: Option
Explanation:

Let AB be the lighthouse and C and D be the positions of the ships.

Then, AB = 100 m, ACB = 30° and ADB = 45°.

AB = tan 30° = 1         AC = AB x 3 = 1003 m.
AC 3

AB = tan 45° = 1         AD = AB = 100 m.
AD

CD = (AC + AD) = (1003 + 100) m
= 100(3 + 1)
= (100 x 2.73) m
= 273 m.

Discussion:
104 comments Page 9 of 11.
Prasad said:   1 decade ago
How to solve the problem I am not under standing for Tan value.
Srinureddy said:   1 decade ago
Hello friends. As best of my knowledge. Here we find the distance between two ships i.e. (AC+AD).

Here we know the height of the lighthouse (AB=100m). For the sake of we taken only (TAN = AB/AC). But not take. Sin&Cos.
Manisha said:   1 decade ago
Why we taken only tan? please explain.
Sumedha said:   1 decade ago
Why we have taken tan and not sin and cos?
Pradeep K Kerketta said:   1 decade ago
How can you manually calculate root 3?
Ram said:   1 decade ago
How can you write AD=AB?
Shro said:   1 decade ago
@Sahil
square root of 3 is 1.73.
So ,add 1.73 + 1 = 2.73
Sahil said:   1 decade ago
How to calculate (root 3 + 1) manually, is there any way ?
Anish kumar said:   1 decade ago
We can also able to find the answer using sin and cos. But more step is needed.
(1)
Sanjana said:   1 decade ago
We can find square roots of any numbers by a special type of division or a method known as column method.
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