Table of contents
- 0. Review of College Algebra4h 43m
- 1. Measuring Angles39m
- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
7. Non-Right Triangles
Law of Sines
Problem 7.39
Textbook Question
A balloonist is directly above a straight road 1.5 mi long that joins two villages. She finds that the town closer to her is at an angle of depression of 35°, and the farther town is at an angle of depression of 31°. How high above the ground is the balloon?
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1
Identify the key elements in the problem: the balloonist's height above the ground (h), the distance between the two villages (1.5 miles), and the angles of depression to the closer village (35°) and the farther village (31°).
Understand that the angles of depression correspond to the angles of elevation from the ground to the balloon when viewed from the villages. Thus, the angles of elevation are also 35° and 31° respectively.
Visualize or draw a diagram with the balloon directly above the midpoint of the line joining the two villages. Label the closer village as point A, the farther village as point B, and the balloon's position vertically above the midpoint as point C. The line segment AB represents the 1.5 miles.
Use trigonometric ratios to set up equations. For the triangle formed by the balloon, the midpoint, and each village: use the tangent function, which relates the opposite side (height of the balloon, h) to the adjacent side (half the distance from the midpoint to each village, 0.75 miles). Set up the equations tan(35°) = h / 0.75 and tan(31°) = h / 0.75.
Solve the system of equations to find the height 'h' of the balloon. Since both equations should ideally give the same height, you can average the results from both equations to find the most accurate height of the balloon.
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