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 1 of 11.
Sakshi said:
2 months ago
The right answer is 273m.
(1)
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)
Raksha said:
1 year ago
Why are we using tan 30°? Please explain to me.
(1)
Yashish yenduva said:
1 year ago
By using tan we can easily get solution.
(4)
Uzma said:
1 year ago
Why we are using tan while we have to find the distance?
i.e why tan =1/√3?
i.e why tan =1/√3?
(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)
Bheemu said:
2 years ago
why tan 30°? Please explain me.
(13)
Akshay said:
2 years ago
Short tricks
(1)30_60_90
1:√3:2.
So,
∆adb
a = 1×100.
= 100m.
b = √3×100.
= 173m.
d = 100 × 2
= 200m.
(2) 45_45_90
1:1:√2.
∆dcb
C = 1×100.
= 100m.
B = 1×100,
= 100m.
D = √2×100.
= 141m.
Total
ADC = 173 + 100,
= 273m.
(1)30_60_90
1:√3:2.
So,
∆adb
a = 1×100.
= 100m.
b = √3×100.
= 173m.
d = 100 × 2
= 200m.
(2) 45_45_90
1:1:√2.
∆dcb
C = 1×100.
= 100m.
B = 1×100,
= 100m.
D = √2×100.
= 141m.
Total
ADC = 173 + 100,
= 273m.
(11)
SAI ESVAR said:
3 years ago
Can anyone explain this problem clearly to understand?
(11)
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