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Question

A ladder is placed against a wall such that its foot is at a distance of 2.5 m from the wall and its top reaches the base of a window 6 m above the ground. Find the length of the ladder.

This question was previously asked in
RRB NTPC 2019 CBT 1 Question Paper (8-Mar-2021) (Shift 2)
The correct answer is
6.5 m

Ladder Length Calculation Using Pythagorean Theorem

The problem describes a scenario that forms a right-angled triangle:

  • The ladder represents the hypotenuse.
  • The distance from the wall to the foot of the ladder is one leg (base).
  • The height the ladder reaches on the wall is the other leg (height).

We can use the Pythagorean theorem, which states $a^2 + b^2 = c^2$, where $a$ and $b$ are the lengths of the legs and $c$ is the length of the hypotenuse.

Applying the Pythagorean Theorem

Let:

  • Base ($b$) = 2.5 m
  • Height ($h$) = 6 m
  • Ladder Length ($L$) = ? (Hypotenuse)

According to the Pythagorean theorem:

$ L^2 = b^2 + h^2 $

Substitute the given values:

$ L^2 = (2.5 \text{ m})^2 + (6 \text{ m})^2 $

Calculate the squares:

  • $ (2.5)^2 = 6.25 $
  • $ (6)^2 = 36 $

Add the results:

$ L^2 = 6.25 + 36 $

$ L^2 = 42.25 $

Find the length ($L$) by taking the square root:

$ L = \sqrt{42.25} $

$ L = 6.5 \text{ m} $

Therefore, the length of the ladder is 6.5 m.

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Similar Questions

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  3. An observer at the top of a tower observes that two cars are running towards the foot of the tower at a distance of 120 m from each other making angles of depression $\alpha$ and $\beta$ such that $\alpha > \beta$ and $\tan \alpha = \sqrt{3}$ and $\tan \beta = \frac{1}{\sqrt{3}}$. Find the height of the tower.
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Important Questions from Heights and Distances

  1. If x is the distance of P from the bottom of the pillar, then consider the following statements :

    1. x can take two values which are in the ratio 1 : 3

    2. x can be equal to the height of the flagstaff

    Which of the statements given above is/are correct?

  2. What is a possible value of tan θ ? 

  3. A vertical tower standing on a levelled field is mounted with a vertical flag staff of length 3 m. From a point on the field, the angles of elevation of the bottom and tip of the flag staff are 30° and 45° respectively. Which one of the following gives the best approximation to the height of the tower?

  4. Two poles are 10 m and 20 m high. The line joining their tops makes an angle of 15° with the horizontal. The distance between the poles is approximately equal to

  5. The angle of elevation of the top of a tower from a point 20 m away from its base is 45 °. What is the height of the tower?

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