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Two pillars of equal heights stand on either side of a roadway, which is 150 m wide. At a point in the roadway between the pillars the elevations of the tops of the pillars are `60^(@) and 30^(@)` . Find the height of the pillars and the position of the point

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To solve the problem, we will follow these steps: ### Step 1: Understand the Problem We have two pillars (AB and CD) of equal height (H) on either side of a roadway that is 150 meters wide. The angles of elevation from a point E in the roadway to the tops of the pillars are 60 degrees for pillar CD and 30 degrees for pillar AB. ### Step 2: Set Up the Diagram Let's denote: - AB as the first pillar on the left. - CD as the second pillar on the right. - The distance between the two pillars (BD) is 150 meters. - The height of both pillars is H. - The distance from point E to pillar AB is BE, and the distance from point E to pillar CD is CE. ### Step 3: Use Trigonometry for Pillar CD From point E, the angle of elevation to the top of pillar CD is 60 degrees. Using the tangent function: \[ \tan(60^\circ) = \frac{H}{CE} \] Since \(\tan(60^\circ) = \sqrt{3}\), we can write: \[ \sqrt{3} = \frac{H}{CE} \implies CE = \frac{H}{\sqrt{3}} \quad \text{(Equation 1)} \] ### Step 4: Use Trigonometry for Pillar AB From point E, the angle of elevation to the top of pillar AB is 30 degrees. Using the tangent function: \[ \tan(30^\circ) = \frac{H}{BE} \] Since \(\tan(30^\circ) = \frac{1}{\sqrt{3}}\), we can write: \[ \frac{1}{\sqrt{3}} = \frac{H}{BE} \implies BE = H \sqrt{3} \quad \text{(Equation 2)} \] ### Step 5: Relate Distances We know that the total distance between the two pillars is: \[ BD = BE + CE = 150 \text{ meters} \] Substituting the values from Equations 1 and 2: \[ 150 = H \sqrt{3} + \frac{H}{\sqrt{3}} \] ### Step 6: Solve for H To combine the terms, we can express them with a common denominator: \[ 150 = H \sqrt{3} + \frac{H}{\sqrt{3}} = H \left(\sqrt{3} + \frac{1}{\sqrt{3}}\right) \] \[ = H \left(\frac{3 + 1}{\sqrt{3}}\right) = H \left(\frac{4}{\sqrt{3}}\right) \] Now, we can solve for H: \[ 150 = H \left(\frac{4}{\sqrt{3}}\right) \] \[ H = \frac{150 \sqrt{3}}{4} = 37.5 \sqrt{3} \] Calculating \(H\): \[ H \approx 64.95 \text{ meters} \] ### Step 7: Find the Position of Point E Using Equation 1 to find CE: \[ CE = \frac{H}{\sqrt{3}} = \frac{64.95}{\sqrt{3}} \approx 37.5 \text{ meters} \] ### Final Results - Height of the pillars (H) is approximately **64.95 meters**. - The distance from point E to pillar AB (BE) is approximately **37.5 meters**.
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ICSE-HEIGHTS AND DISTANCES -Exercise 22 B
  1. In the figure, given below, it is given that AB is perpendicular ot BD...

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  2. Find the height of a tree it is found that on walking away from is 20 ...

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  3. Find the height of a building, when it is found that on walking toward...

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  4. From the top of a light house 100 m high, t he angles of depression of...

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  5. From the top of a light house 100 m high, t he angles of depression of...

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  6. Two pillars of equal heights stand on either side of a roadway, which ...

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  7. From the figure, given below . calculate the length of CD

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  8. The angle of elevation of the top of a tower is observed to be 60^(@) ...

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  9. The angle of elevation of the top of a tower is observed to be 60^(@) ...

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  10. From the top of a building 60m high the angles of depression of the...

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  11. A man on a cliff observes a boat, at an angle of depression 30^(@) , w...

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  12. A man on a cliff observes a boat, at an angle of depression 30^(@) , w...

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  13. A man in a boat rowing away from a lighthouse 150 m high, takes2 minut...

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  14. A person standing on the bank of a river observes that the angle of ...

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  15. A person standing on the bank of a river observes that the angle of ...

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  16. The horizontal distance between two towers is 75 m and the angular de...

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  17. The length of the shadow of a tower standing of level plane is found ...

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

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  19. From the top of a hill, the angles of depression of two consecutive ki...

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