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 2 of 11.
Masthan shaik said:
8 years ago
√3 means the square of 3.
It calculated as 1.732. Because two same numbers give their square root.
i;e 2 * 2 = 4,3 * 3 = 9 just like this 1.732 * 1.732 = 2.999824 it is nearest to 3 then 1.732 is square root of 3.
It calculated as 1.732. Because two same numbers give their square root.
i;e 2 * 2 = 4,3 * 3 = 9 just like this 1.732 * 1.732 = 2.999824 it is nearest to 3 then 1.732 is square root of 3.
Siddhant Acharya said:
10 years 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).
DINESH RANA said:
10 years 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.
Bharath said:
5 months ago
We use tan because we know tan is opp by the adjutant.
The opp value is 100 which means the height of the lighthouse, we should know the distance between the two ships so we want the adjacent side.
The opp value is 100 which means the height of the lighthouse, we should know the distance between the two ships so we want the adjacent side.
(3)
Pooja said:
7 months ago
Simple explanation:
The formula of tan; θ is,
tan θ = opposite side/adjacent side
So, we have angles 30° and 45° and the opposite side 100 m.
So, we can find an adjacent side.
The formula of tan; θ is,
tan θ = opposite side/adjacent side
So, we have angles 30° and 45° and the opposite side 100 m.
So, we can find an adjacent side.
(1)
Preetam said:
8 years ago
We have taken tan. Instead of sin or cos because perpendicular is given and we need to find the base, so tan is equal to perpendicular/base. So for that, we need a tan.
Yeshi samdup said:
5 years ago
Sine=opp/hyp.
Cos=adj/hyp..
Tan=opp/adj.
Tan30 = 100/CA.
CA = 100/tan30,
CA = 173.
Tan45 = 100/AD.
AD = 100/tan45,
AD = 100.
Therefore, CA+AD.
173+100.
=273.
Cos=adj/hyp..
Tan=opp/adj.
Tan30 = 100/CA.
CA = 100/tan30,
CA = 173.
Tan45 = 100/AD.
AD = 100/tan45,
AD = 100.
Therefore, CA+AD.
173+100.
=273.
(3)
Chand said:
1 year ago
Sin30 = 100/B.
1/2 = 100/B.
B = 200.
Sin45 = 100/B.
1/√2 = 100/B,
B = 100×√2,
B = 100×1.41.
B = 141,
B+B = 200 + 141,
= 341.
1/2 = 100/B.
B = 200.
Sin45 = 100/B.
1/√2 = 100/B,
B = 100×√2,
B = 100×1.41.
B = 141,
B+B = 200 + 141,
= 341.
(4)
Bhupal said:
1 decade ago
From triangle bca we know only value of ba & bca cone and we find ac i.e. base from trigonmetric formula tan is best because tan=vertical/base.
Bhupal said:
1 decade ago
From triangle bca we know only value of ba & bca cone and we find ac i.e. base from trigonmetric formula tan is best because tan=vertical/base.
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