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An observer on the top of a cliff, 200 m...

An observer on the top of a cliff, 200 m above the sea-level, observes the angles of depression of the two ships to be `45^(@) and 30^(@)` respectively. Find the distance between the ships, if the ships are
on the same side of the cliff,

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To solve the problem, we will follow these steps: ### Step 1: Understand the problem and draw a diagram We have a cliff that is 200 m high. From the top of the cliff, an observer sees two ships at angles of depression of 45° and 30°. We need to find the distance between the two ships. ### Step 2: Label the diagram Let: - Point P be the top of the cliff. - Point Q be the sea level (200 m below P). - Point A be the position of the first ship (at 45° angle of depression). - Point B be the position of the second ship (at 30° angle of depression). ### Step 3: Identify the triangles We will use two right triangles: 1. Triangle PBQ for ship B (angle of depression = 30°) 2. Triangle PAQ for ship A (angle of depression = 45°) ### Step 4: Use the tangent function to find distances For triangle PBQ: - The angle of depression to ship B is 30°. Therefore, angle QPB = 30°. - The height of the cliff (PQ) is the opposite side = 200 m. - The distance from the base of the cliff to ship B (BQ) is the adjacent side. Using the tangent function: \[ \tan(30°) = \frac{PQ}{BQ} \] \[ \tan(30°) = \frac{200}{BQ} \] We know that \(\tan(30°) = \frac{1}{\sqrt{3}}\): \[ \frac{1}{\sqrt{3}} = \frac{200}{BQ} \] Cross-multiplying gives: \[ BQ = 200\sqrt{3} \] ### Step 5: Calculate BQ Using the approximate value of \(\sqrt{3} \approx 1.732\): \[ BQ \approx 200 \times 1.732 \approx 346.4 \text{ m} \] ### Step 6: Calculate distance for ship A For triangle PAQ: - The angle of depression to ship A is 45°. Therefore, angle QPA = 45°. - Again, the height of the cliff (PQ) is the opposite side = 200 m. - The distance from the base of the cliff to ship A (AQ) is the adjacent side. Using the tangent function: \[ \tan(45°) = \frac{PQ}{AQ} \] \[ \tan(45°) = \frac{200}{AQ} \] We know that \(\tan(45°) = 1\): \[ 1 = \frac{200}{AQ} \] Cross-multiplying gives: \[ AQ = 200 \] ### Step 7: Find the distance between the ships The distance between the two ships (AB) is given by: \[ AB = BQ - AQ \] Substituting the values we found: \[ AB = 346.4 - 200 = 146.4 \text{ m} \] ### Final Answer The distance between the ships is **146.4 meters**. ---
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ICSE-HEIGHTS AND DISTANCES -Exercise 22 C
  1. An observer on the top of a cliff, 200 m above the sea-level, observes...

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  2. Find AD

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  3. Find AD

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  4. In the following diagram, AB is a floor-board, PQRS is a cubical box w...

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  5. Calculate BC

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  6. Calculate AB

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  7. The radius of a circle is given as 15 cm and chord AB subtends an angl...

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  8. The radius of a circle is given as 15 cm and chord AB subtends an angl...

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  9. At a point on level ground, the angle of elevation of a vertical to...

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  10. A vertical tower stands on a horizontal plane and is surmounted by a v...

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  11. With reference to the given figure, a man stands on the ground at poin...

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  12. With reference to the given figure, a man stands on the ground at poin...

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  13. The angles of elevation of the top of a tower from two points at a dis...

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  14. From a window A , 10 m above the ground the angle of elevation of the...

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  15. A vertical tower is 20 m high. A man standing at some distance from th...

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  16. A man standing on the bank of a river observes that the angle of elev...

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  17. A man standing on the bank of a river observes that the angle of elev...

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  18. A 20 m high vertical pole and a vertical tower are on the same level g...

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  19. A 20 m high vertical pole and a vertical tower are on the same level g...

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  20. A vertical pole and a vertical tower are on the same level ground in ...

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  21. A vertical pole and a vertical tower are on the same level ground in ...

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