From the top of a platform 7 m high, the angle of elevation of a tower was 30°. If the platform was positioned 50√3 m away from the tower, how tall was the tower?
57 m
This problem involves using trigonometry to find the height of a tower. We are given the height of a platform, the horizontal distance from the platform to the tower, and the angle of elevation from the top of the platform to the top of the tower.
Let's break down the given information:
We need to find the total height of the tower.
Imagine the platform and the tower standing vertically on the ground. The horizontal distance between them forms the base. From the top of the 7m high platform, a line of sight to the top of the tower creates the angle of elevation. If we draw a horizontal line from the top of the platform towards the tower, this line will be parallel to the ground and \(50\sqrt{3}\) m long. This horizontal line and the vertical segment representing the part of the tower above the platform's height form a right-angled triangle.
Let:
The total height of the tower is the sum of the platform's height and the additional height 'y', i.e., \(H = h + y\).
The angle of elevation (30°) is formed in the right-angled triangle between the horizontal line from the platform top and the line of sight to the tower top. In this triangle:
We can use the tangent function, which relates the opposite side and the adjacent side in a right-angled triangle:
\(\tan(\text{angle of elevation}) = \frac{\text{Opposite side}}{\text{Adjacent side}}\)
In our case:
\(\tan(30^\circ) = \frac{y}{x}\)
Substitute the known values:
\(\tan(30^\circ) = \frac{y}{50\sqrt{3}}\)
We know that the value of \(\tan(30^\circ)\) is \(\frac{1}{\sqrt{3}}\).
So, the equation becomes:
\(\frac{1}{\sqrt{3}} = \frac{y}{50\sqrt{3}}\)
Now, we can solve for 'y':
\(y = \frac{1}{\sqrt{3}} \times 50\sqrt{3}\)
\(y = 50\) m
So, the height of the tower above the platform's top is 50 m.
The total height of the tower is the height of the platform plus the height calculated above:
\(H = h + y\)
\(H = 7 \, \text{m} + 50 \, \text{m}\)
\(H = 57 \, \text{m}\)
Thus, the total height of the tower is 57 m.
| Parameter | Value |
|---|---|
| Platform Height (h) | 7 m |
| Horizontal Distance (x) | \(50\sqrt{3}\) m |
| Angle of Elevation | 30° |
| Height above Platform (y) | Calculated as 50 m |
| Total Tower Height (H) | Calculated as 57 m |
| Concept | Description | Trigonometric Ratio |
|---|---|---|
| Angle of Elevation | The angle between the horizontal line of sight and the line of sight upwards to an object. | Used in calculations involving looking upwards. |
| Angle of Depression | The angle between the horizontal line of sight and the line of sight downwards to an object. | Used in calculations involving looking downwards. |
| Tangent (\(\tan\)) | Ratio of the length of the side opposite the angle to the length of the side adjacent to the angle in a right-angled triangle. | \(\tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}}\) |
| Sine (\(\sin\)) | Ratio of the length of the side opposite the angle to the length of the hypotenuse. | \(\sin(\theta) = \frac{\text{Opposite}}{\text{Hypotenuse}}\) |
| Cosine (\(\cos\)) | Ratio of the length of the side adjacent to the angle to the length of the hypotenuse. | \(\cos(\theta) = \frac{\text{Adjacent}}{\text{Hypotenuse}}\) |
Problems involving heights and distances often require drawing a diagram to represent the situation correctly. Identifying the right-angled triangle is crucial. Based on what is given (angles, sides) and what needs to be found, you choose the appropriate trigonometric ratio (sin, cos, tan).
Remember common trigonometric values for standard angles like 0°, 30°, 45°, 60°, and 90°. In this problem, the value of \(\tan(30^\circ)\) was essential.
Always ensure your calculations are accurate and pay attention to the units of measurement.
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