Home
Class 10
MATHS
The angle of elevation of the top of a t...

The angle of elevation of the top of a tower from a point on the ground is `30^(@)`. After walking 45 m towards the tower, the angle of elevation becomes `45^(@)`. Find the height of the tower.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we will use trigonometric ratios and the concept of right triangles. Let's break down the solution step by step. ### Step 1: Understand the Problem We have a tower and two points on the ground where the angles of elevation to the top of the tower are given. The first angle of elevation is \(30^\circ\) from point A, and after walking 45 m towards the tower to point B, the angle of elevation becomes \(45^\circ\). ### Step 2: Set Up the Diagram Let's denote: - \(h\) = height of the tower - \(d\) = distance from point A to the base of the tower - Point A is where the angle of elevation is \(30^\circ\). - Point B is where the angle of elevation is \(45^\circ\). From point A, the distance to the tower is \(d\). After walking 45 m towards the tower, the distance from point B to the tower is \(d - 45\). ### Step 3: Apply Trigonometric Ratios Using the tangent function, we can set up the following equations based on the angles of elevation: 1. From point A: \[ \tan(30^\circ) = \frac{h}{d} \] Since \(\tan(30^\circ) = \frac{1}{\sqrt{3}}\), we have: \[ \frac{1}{\sqrt{3}} = \frac{h}{d} \implies h = \frac{d}{\sqrt{3}} \quad \text{(Equation 1)} \] 2. From point B: \[ \tan(45^\circ) = \frac{h}{d - 45} \] Since \(\tan(45^\circ) = 1\), we have: \[ 1 = \frac{h}{d - 45} \implies h = d - 45 \quad \text{(Equation 2)} \] ### Step 4: Solve the Equations Now we have two equations: 1. \(h = \frac{d}{\sqrt{3}}\) 2. \(h = d - 45\) We can set them equal to each other: \[ \frac{d}{\sqrt{3}} = d - 45 \] ### Step 5: Rearranging the Equation Multiply both sides by \(\sqrt{3}\) to eliminate the fraction: \[ d = \sqrt{3}(d - 45) \] Expanding the right side: \[ d = \sqrt{3}d - 45\sqrt{3} \] Now, rearranging gives: \[ d - \sqrt{3}d = -45\sqrt{3} \] Factoring out \(d\): \[ d(1 - \sqrt{3}) = -45\sqrt{3} \] Thus, \[ d = \frac{-45\sqrt{3}}{1 - \sqrt{3}} \] ### Step 6: Calculate \(d\) To simplify \(d\), multiply the numerator and denominator by the conjugate of the denominator: \[ d = \frac{-45\sqrt{3}(1 + \sqrt{3})}{(1 - \sqrt{3})(1 + \sqrt{3})} = \frac{-45\sqrt{3}(1 + \sqrt{3})}{1 - 3} = \frac{-45\sqrt{3}(1 + \sqrt{3})}{-2} = \frac{45\sqrt{3}(1 + \sqrt{3})}{2} \] ### Step 7: Substitute Back to Find \(h\) Now substitute \(d\) back into either Equation 1 or Equation 2 to find \(h\). Using Equation 2: \[ h = d - 45 \] Substituting \(d\): \[ h = \frac{45\sqrt{3}(1 + \sqrt{3})}{2} - 45 \] ### Step 8: Calculate the Height \(h\) Now, calculate \(h\): \[ h = \frac{45\sqrt{3}(1 + \sqrt{3}) - 90}{2} \] This will give us the height of the tower. ### Final Answer After performing the calculations, we find that the height of the tower \(h\) is approximately \(h \approx 45\) m.
Promotional Banner

Topper's Solved these Questions

  • SOME APPLICATIONS OF TRIGONOMETRY

    NAGEEN PRAKASHAN|Exercise Revision Exercise (short Answer Questions)|5 Videos
  • SOME APPLICATIONS OF TRIGONOMETRY

    NAGEEN PRAKASHAN|Exercise Revision Exercise (long Answer Questions)|1 Videos
  • SOME APPLICATIONS OF TRIGONOMETRY

    NAGEEN PRAKASHAN|Exercise Long Answer Questions|5 Videos
  • REAL NUMBERS

    NAGEEN PRAKASHAN|Exercise Revision Exercise Long Answer Questions|5 Videos
  • STATISTICS

    NAGEEN PRAKASHAN|Exercise Revision Exercise Long Answer Questions|5 Videos

Similar Questions

Explore conceptually related problems

The angle of elevation of the top of a tower from a point on the ground is 30^(@) . After walking 40sqrt3 m towards the tower, the angle of elevation becomes 60^(@) . Find the height of the tower.

The angle of elevation of the top of a tower at a point G on the ground is 30^(@) . On walking 20 m towards the tower the angle of elevation becomes 60^(@) . The height of the tower is equal to :

Problems of finding the height of tower if angle of elevation is changing on walking away/towards the tower.ex-1The angle of the elevation of the top of the tower at a point on the ground is 30^(0). On walking 24m towards the tower the angle of elevation changes from 60^(0). Find the height of the tower.

The angle of elevation of the top of a tower at a point A on the ground is 30^(@) . On walking 20 meters toward the tower, the angle of elevation is 60^(@) . Find the height of the tower and its distance from A.

The angle of elevation of the top of a tower at a point on the ground is 30o.On walking 24m towards the tower,the angle of elevation becomes 60_(0). Find the height of the tower.

The angle of elevation of the top of a tower at a point on level ground is 45^(@). When moved 20 m towards the tower, the angle of elevation becomes 60^(@). What is the height of the tower ?

The elevation of the top of a tower from a point on the ground is 45^(@) . On travelling 60 m from the point towards the tower, the alevation of the top becomes 60^(@) . The height of the tower, in metres, is

NAGEEN PRAKASHAN-SOME APPLICATIONS OF TRIGONOMETRY-Exercise
  1. The upper part of a tree broken over by wind, makes an angle of 30^(@)...

    Text Solution

    |

  2. In a violent storm, a tree got bent by the wind. The top of the tree m...

    Text Solution

    |

  3. The angle of elevation of the top of a tower from a point on the groun...

    Text Solution

    |

  4. There are two points on the horizontal line passing through the foot o...

    Text Solution

    |

  5. From the top of a light house, the angles of depression of two ships o...

    Text Solution

    |

  6. From the top of a light-hours, the angles of depression of two ships o...

    Text Solution

    |

  7. An aeroplane, when 3000 m high, passes vertically above anthoer aeropl...

    Text Solution

    |

  8. The angle of elevation of the top of am incomplete temple, at a point ...

    Text Solution

    |

  9. The angle of elevation of the top of an incomplete tower, at a point 4...

    Text Solution

    |

  10. On a straight line passing through the foot of a tower, two points C a...

    Text Solution

    |

  11. The angle of elevation of the top of a tower from the foot of a house,...

    Text Solution

    |

  12. There is a 7m high statue standing on a cliff. At a point P on the gro...

    Text Solution

    |

  13. The distance between two towers is 140 m while seeing from the top if ...

    Text Solution

    |

  14. A temple and a flagstaff surmounted at its top, each subtends equal an...

    Text Solution

    |

  15. A 7 m long flagstaff is fixed on the top of a tower on the horizontal...

    Text Solution

    |

  16. At one side of a road, there os a house and on the other side there is...

    Text Solution

    |

  17. A tower subtends an angle of 60^(@) at a point on the plane passing th...

    Text Solution

    |

  18. An aeroplane is flying over two houses which are at a distance of 300 ...

    Text Solution

    |

  19. From the top of a 96 m tower, the angles of depression of two cars, on...

    Text Solution

    |

  20. The angle of elevation of the top of a vertical tower, from a point in...

    Text Solution

    |