Aptitude - Height and Distance - Discussion
Discussion Forum : Height and Distance - General Questions (Q.No. 1)
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:
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 10 of 11.
Ramya said:
7 years ago
Please explain me the solution clearly.
Mano said:
7 years ago
Why using tan here?
Yogita sable said:
7 years ago
I am not getting it. Please explain in details.
Garalapati bharadwaja said:
7 years ago
Why should we take only tan? Anyone explain me.
Naveen said:
7 years ago
Why should we take tan? Anyone explain me.
Kishor said:
7 years ago
How? tan 45° = 1
AD = AB = 100 m. How it is? Explain in detail.
AD = AB = 100 m. How it is? Explain in detail.
Kowsalyadevi said:
6 years ago
First, understand the problem from the given Diagram.
We have to find the distance of the CD.
So, first identify how to use 45° and 35°.
Only by using tan because we know AB value
We know that tanx = perpendicular/base.
tan 30° = AB/CA.
1/√3= 100/CA.
CA=100 x √3.
tan 45° = AB/AD.
1 = 100/AD,
AD = 100.
We know that CD = CA+CD.
= 100x√ 3+100,
= 100(√3+1),
= 100(1.73+1),
= 100(2.73),
= 273m.
We have to find the distance of the CD.
So, first identify how to use 45° and 35°.
Only by using tan because we know AB value
We know that tanx = perpendicular/base.
tan 30° = AB/CA.
1/√3= 100/CA.
CA=100 x √3.
tan 45° = AB/AD.
1 = 100/AD,
AD = 100.
We know that CD = CA+CD.
= 100x√ 3+100,
= 100(√3+1),
= 100(1.73+1),
= 100(2.73),
= 273m.
Divakar said:
6 years ago
What is the reason to take tan? Please tell me.
Mrinayak said:
6 years ago
How to find the √3 value? Please explain the process.
Likitha said:
6 years ago
Thanks all for explaining clearly.
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