Math Problem Statement
To find the height of a flagpole, a student stands a random distance away from it and measures the angle ofelevation from her feet to the top of the flagpole to be 70o. The student then moves 2m further away from the flagpole in the same line of sight as before, and notices that the new angle of elevationas measured before isnow60o. Draw a diagram depicting the situation, then calculate the height of the flagpole
Solution
To solve this problem, we'll use trigonometry, specifically the tangent function, which relates the angle of elevation to the height and distance of the object. Let's break down the steps and draw the diagram.
Step 1: Draw the Diagram
- Draw a vertical line representing the flagpole with height .
- Mark two points on the ground along the same line of sight:
- The first point , where the student is initially standing, is a distance away from the base of the flagpole.
- The second point , where the student moves 2 meters further away, is a distance from the base of the flagpole.
- Draw the horizontal ground line connecting the base of the flagpole to both points and .
- Draw two lines from points and to the top of the flagpole, forming angles of elevation and respectively.
This will create two right triangles, and , where:
- is the height of the flagpole,
- is the distance from the flagpole to point ,
- is the distance from the flagpole to point ,
- (angle of elevation from point ),
- (angle of elevation from point ).
Step 2: Set Up Equations Using Tangent
For the first position (at point ): So,
For the second position (at point ): So,
Step 3: Set Up the Equation to Solve for and
Since both expressions represent the height , we can set them equal to each other:
Expanding and solving for :
Step 4: Calculate and then
Substituting the values of the tangents:
Now, calculate :
Final Answer:
The height of the flagpole is approximately 9.37 meters.
Would you like further details on any part of the solution? Here are some related questions:
- What other trigonometric identities could be used to solve similar problems?
- How would the problem change if the student moved closer to the flagpole?
- Can this method be applied to non-right triangles? How?
- How does the accuracy of the angle measurements affect the result?
- What if the ground was not level, how would that affect the calculations?
Tip: Always ensure that your calculator is set to the correct mode (degrees/radians) when solving trigonometric problems.
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Math Problem Analysis
Mathematical Concepts
Trigonometry
Angle of Elevation
Tangent Function
Formulas
tan(θ) = opposite / adjacent
h = x * tan(θ1)
h = (x + 2) * tan(θ2)
Theorems
Trigonometric Ratios in Right Triangles
Suitable Grade Level
Grades 10-12
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