Aptitude - Height and Distance - Discussion

Discussion Forum : Height and Distance - General Questions (Q.No. 3)
3.
The angle of elevation of a ladder leaning against a wall is 60° and the foot of the ladder is 4.6 m away from the wall. The length of the ladder is:
2.3 m
4.6 m
7.8 m
9.2 m
Answer: Option
Explanation:

Let AB be the wall and BC be the ladder.

Then, ACB = 60° and AC = 4.6 m.

AC = cos 60° = 1
BC 2

BC = 2 x AC
= (2 x 4.6) m
= 9.2 m.

Discussion:
45 comments Page 4 of 5.

Altamash Bagwan said:   6 years ago
In this question, cos indicate is an adjacent side/hypotenuse side.

Rahul said:   5 years ago
In the question, it's given that the foot of the ladder is 4.6m away from the wall. And we could take the given parameter to be either BC or AC. If it is the length of the ladder, then we should use sin and otherwise tan.

Jimuta said:   5 years ago
Why it will not be 7.8?

Also, we can take tan60,

AB/AC = tan60, =>AB=AC * tan60 =>AB= 4.6*tan60.

Jayanth said:   5 years ago
Here, they asked about the length of the ladder, not about the hypotenuse.

So the correct answer is 7.8m.
(1)

Zan De19 said:   5 years ago
@All.

Take, Sin or Cos or Tan;

Sin = opposite/hypothesis
Cos = adjacent/hypothesis
Tan = opposite/adjacent.

Given are as following;

The angle is 60 degree.

The foot of leader is 4.6 m away from the wall (CA) this means 4.6m is adjacent,
A leader is leaning on the wall (CB) this will be hypothesis while determining (adjacent opposite or hypothesis but in real sense, it's the length of the leader!
Now, we can make out that it's Cos and not tan or sin because adjacent CA is given (4.6m) while hypothesis CB is x or unknown.

So,
Cos60 = CA/CB.
CB(x) = 4.6/cos60.
x = 9.2.

Thank You.

Anil kumar behera said:   5 years ago
We all know that tan 60=AB/AC.
then, √(3)=AB/4.6,
then,4.6*√(3)=AB,
AB = 1.732 * 4.6.
AB = 7.967.
AB = 8.
(5)

GAGAN said:   4 years ago
@Anil Kumar.

But they have asked BC not AB. Why are you finding AB?
(1)

Yeshi Samdup said:   4 years ago
Cos = adj/hyp
Cos60= 4.6m/hyp
0.5= 4.6m/hyp
Hyp= 4.6m/.
Therefore Hyp or length of ladder is 9.2m.
(4)

Deepali said:   4 years ago
why we take cos here? Explain please.
(1)

Lorddidah said:   4 years ago
Simply remember the code SOHCAHTOA.

SOH - Sine = Opposite/Hypotenuse.
CAH - Cos = Adjacent/Hypotenuse.
TOA - Tan = Opposite/Adjacent.
(4)


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