Engineering Board Exam Reviewer · Solutions to Right Triangles · medium
ECE Board April 1994: A pole cast a shadow 15 m long when the angle of elevation of the sun is 61°. If the pole is leaned 15° from the vertical directly towards the sun, determine the length of the pole.
- 54.23 m
- 48.23 m
- 42.44 m
- 46.21 m
Answer
A. 54.23 m
Solution
In the triangle formed by the pole, its shadow, and the sun's ray: the angle between the pole and the ground (shadow side) is 180°-75°=105° (the pole makes 75° with the ground on the sun's side, since it leans 15° from vertical), the angle at the shadow's tip is 61°, so the angle at the pole's tip is 180°-105°-61°=14°. By the Law of Sines: L/ 61°=15/ 14° L=15 61°/ 14° 54.23 m.
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