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If the elevation of the sun is 30^@ , th...

If the elevation of the sun is `30^@` , then the length of the shadow cast by a tower of 150 ft. height is

A

`75sqrt3` ft.

B

`200sqrt3` ft

C

`150sqrt3` ft.

D

none of these

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The correct Answer is:
To find the length of the shadow cast by a tower of height 150 ft when the elevation of the sun is 30 degrees, we can use the concept of right triangles and trigonometric ratios. ### Step-by-Step Solution: 1. **Understand the Problem**: We have a tower of height \( h = 150 \) ft. The angle of elevation of the sun is \( \theta = 30^\circ \). We need to find the length of the shadow \( S \). 2. **Draw a Diagram**: Visualize a right triangle where: - The height of the tower is the vertical side (150 ft). - The length of the shadow is the horizontal side (S). - The angle of elevation from the tip of the shadow to the top of the tower is \( 30^\circ \). 3. **Use the Tangent Function**: The tangent of the angle of elevation is defined as the ratio of the opposite side (height of the tower) to the adjacent side (length of the shadow): \[ \tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}} = \frac{h}{S} \] Substituting the known values: \[ \tan(30^\circ) = \frac{150}{S} \] 4. **Calculate \( \tan(30^\circ) \)**: We know from trigonometric tables that: \[ \tan(30^\circ) = \frac{1}{\sqrt{3}} \approx 0.577 \] 5. **Set Up the Equation**: Now substituting this value into the equation: \[ \frac{1}{\sqrt{3}} = \frac{150}{S} \] 6. **Cross-Multiply to Solve for \( S \)**: \[ S = 150 \cdot \sqrt{3} \] 7. **Calculate the Length of the Shadow**: Using the approximate value of \( \sqrt{3} \approx 1.732 \): \[ S \approx 150 \cdot 1.732 \approx 259.8 \text{ ft} \] ### Final Answer: The length of the shadow cast by the tower is approximately \( 259.8 \) ft. ---
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OBJECTIVE RD SHARMA-HEIGHTS AND DISTANCES-Exercise
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  2. A man of height 6 ft. observes the top of a tower and the foot of th...

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  3. If the elevation of the sun is 30^@ , then the length of the shadow c...

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  4. A ladder rests against a vertical wall at angle alpha to the horizonta...

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  5. From the top of a cliff 300 metres high, the top of a tower was obser...

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  6. The angles of elevation of the top of a tower at the top and the foot ...

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  7. A person standing on the bank of a river finds that the angle of elev...

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  8. A tower subtends an angle of 30^@ at a point on the same level as the ...

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  9. AB is a vertical pole and C is its mid point. The end A is on the leve...

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  10. The angle of depression of a point situated at a distance of 70 metres...

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  11. The angle of elevation of the top of a vertical tower from two points ...

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  12. An aeroplane flying horizontally , 1km above the ground , is observed...

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  13. At the foot of the mountain the elevation of its summit is 45^@, after...

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  14. At a distance 12 metres from the foot A of a tower AB of height 5 met...

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  15. A tower 50 m high , stands on top of a mount, from a point on the grou...

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  16. A person on a ship sailing north sees two lighthouses which are 6 km a...

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  17. An observer finds that the elevation of the top of a tower is 22.5^@ a...

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  18. A vertical lamp-post, 6m high, stands at a distance of 2 m from a wall...

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  19. The angle of elevation of the top of a vertical pole when observed ...

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  20. The upper (3/4)^(th) portion of a vertical pole subtends an angle "tan...

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