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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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  2. A tree broke at a height of 8 m from its foot and the broken upper part touches the ground at a point of 6 m from its foot. Find the height of the tree.
  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. Two ships are sailing in the sea on the two sides of a lighthouse. The angles of elevation of the top of the lighthouse as observed from the ships are 45 ° and 60° respectively. If the lighthouse is 81 m high, then the distance between two ships is:

  2. The horizontal distance between two towers is 40√3 m. The angle of depression of the top of the first tower when seen from the top of the second tower is 30°. If the height of the second tower is 130 m, find the height of the first tower.

  3. The angle of elevation of a ladder leaning against a house is 60° and the foot of the ladder is 6.5 metres from the house. The length of the ladder is

  4. A kite is flying at a height of 50 m. If the length of the string is 100 m then the inclination of the string to the horizontal ground in degree measures is:

    A. 90

    B. 45

    C. 60

    D. 30

  5. Two poles of the height 15 m and 20 m stand vertically upright on a plane ground. If the distance between their feet is 12 m, find the distance between their tops.

    A. 11 m

    B. 12 m

    C. 13 m

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