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:
106 comments Page 6 of 11.
Ganesh said:
1 decade ago
Just try to understand.
We need to find AC and we know only AB.
BY P. Theorem, perpendicular/base, i.e.. AB/AC i.e., = tan.
1) We didn't know the value CB, if we take AB/CB no AC omit this.
2) AC/CB both value not known so no chance.
3) There is nothing called AC/AB mean base/perpendicular cancel this.
That's it try to read formula section you will understand.
We need to find AC and we know only AB.
BY P. Theorem, perpendicular/base, i.e.. AB/AC i.e., = tan.
1) We didn't know the value CB, if we take AB/CB no AC omit this.
2) AC/CB both value not known so no chance.
3) There is nothing called AC/AB mean base/perpendicular cancel this.
That's it try to read formula section you will understand.
Siddhant Acharya said:
1 decade ago
It has been asked the distance between the two ships not the distance between the peak of the lighthouse and the ship. The one which has an elevation of 30 degrees will have a different value rather than (100 root 3).
Anjum shaikh said:
1 decade ago
Can you give me trigonometry formula which are use to solve height and length of problem?
How can we solve problem in less time logically?
How can we solve problem in less time logically?
DINESH RANA said:
1 decade ago
Simply we can easily solve the problem.
We can use the trigonometric formula:
As we know that:
(1) sinx = perpendicular/hypotenuse.
(2) cosx = base/hypotenuse and third one is a.
(3) tanx = perpendicular/base.
We can use the trigonometric formula:
As we know that:
(1) sinx = perpendicular/hypotenuse.
(2) cosx = base/hypotenuse and third one is a.
(3) tanx = perpendicular/base.
P.Dhana lakshmi said:
10 years ago
Nice explanations, Thank you all.
AKASH RAI said:
10 years ago
Then, AB = 100 m, ACB = 30° and ADB = 45°.
AB = tan 30° = 1, AC = AB x 3 = 1003 m.
AC = 1003 m.
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.
That Proved.
AB = tan 30° = 1, AC = AB x 3 = 1003 m.
AC = 1003 m.
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.
That Proved.
Kavya sreeram said:
10 years ago
Tan 30 is 1/√3 right? then in all problem, it is 1, how come?
Radhika Mane said:
10 years ago
How to take root 3 value?
Ram said:
10 years ago
I do not understand. Please, anyone, give a simple explanation.
Akhilesh Agrahari said:
10 years ago
By taking 100 common in 100 and 100root3.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers