Home
Class 12
MATHS
The angle of elevation of the top of a t...

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.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem step by step, we will use trigonometric relationships involving the angles of elevation. ### 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 from point A is \(30^\circ\), and after walking 20 meters towards the tower, the angle of elevation becomes \(60^\circ\). We need to find the height of the tower and the distance from point A to the base of the tower. ### Step 2: Set Up the Diagram Let's denote: - The height of the tower as \(h\). - The distance from point A to the base of the tower as \(x\). - After walking 20 meters towards the tower, the new distance from point B (the new position) to the base of the tower is \(x - 20\). ### Step 3: Use the First Angle of Elevation From point A, using the angle of elevation \(30^\circ\): \[ \tan(30^\circ) = \frac{h}{x} \] We know that \(\tan(30^\circ) = \frac{1}{\sqrt{3}}\), so we can write: \[ \frac{1}{\sqrt{3}} = \frac{h}{x} \] This gives us: \[ h = \frac{x}{\sqrt{3}} \quad \text{(Equation 1)} \] ### Step 4: Use the Second Angle of Elevation From point B, using the angle of elevation \(60^\circ\): \[ \tan(60^\circ) = \frac{h}{x - 20} \] We know that \(\tan(60^\circ) = \sqrt{3}\), so we can write: \[ \sqrt{3} = \frac{h}{x - 20} \] This gives us: \[ h = \sqrt{3}(x - 20) \quad \text{(Equation 2)} \] ### Step 5: Set the Two Equations for Height Equal Now we have two expressions for \(h\): 1. \(h = \frac{x}{\sqrt{3}}\) 2. \(h = \sqrt{3}(x - 20)\) Setting them equal to each other: \[ \frac{x}{\sqrt{3}} = \sqrt{3}(x - 20) \] ### Step 6: Solve for \(x\) Multiply both sides by \(\sqrt{3}\) to eliminate the fraction: \[ x = 3(x - 20) \] Expanding the right side: \[ x = 3x - 60 \] Rearranging gives: \[ 60 = 3x - x \] \[ 60 = 2x \] \[ x = 30 \] ### Step 7: Find the Height \(h\) Now substitute \(x = 30\) back into Equation 1 to find \(h\): \[ h = \frac{30}{\sqrt{3}} = 10\sqrt{3} \] ### Step 8: Conclusion The height of the tower is \(10\sqrt{3}\) meters, and the distance from point A to the base of the tower is \(30\) meters. ### Summary of Results - Height of the tower \(h = 10\sqrt{3}\) meters - Distance from point A to the base of the tower \(x = 30\) meters
Promotional Banner

Topper's Solved these Questions

  • HEIGHTS & DISTANCE

    FIITJEE|Exercise ASSIGNMENT PROBLEMS (OBJECTIVE) LEVEL-I|20 Videos
  • HEIGHTS & DISTANCE

    FIITJEE|Exercise ASSIGNMENT PROBLEMS (OBJECTIVE) LEVEL-II|20 Videos
  • HEIGHTS & DISTANCE

    FIITJEE|Exercise EXERCISE 1:|3 Videos
  • FUNCTION

    FIITJEE|Exercise NUMERICAL BASED|3 Videos
  • HYPERBOLA

    FIITJEE|Exercise NUMERICAL BASED|4 Videos

Similar Questions

Explore conceptually related problems

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 :

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 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.

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 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 ?

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 any point on the ground is 30^@ and moving 20 metres towards the tower it becomes 60^@ . The height of the tower is