Subjects trigonometry

Pole Length E6A9B4

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Question: When the angle of elevation of the sun is $62^\circ$, a telephone pole that is tilted at an angle of $8^\circ$ directly away from the sun casts a shadow $21$ feet long. Determine the length of the pole to the nearest foot.
1. **State the problem:** We need to find the length of a telephone pole that is tilted $8^\circ$ away from the sun when the sun's elevation angle is $62^\circ$ and the shadow length is $21$ feet. 2. **Understand the setup:** The sun's rays form a $62^\circ$ angle with the horizontal ground. The pole is tilted $8^\circ$ away from the sun's direction, so the angle between the pole and the ground is $62^\circ - 8^\circ = 54^\circ$. 3. **Identify the right triangle:** The shadow forms the adjacent side to the pole's angle with the ground, and the pole length is the hypotenuse. 4. **Use the cosine function:** For angle $\theta = 54^\circ$, the cosine relates the adjacent side (shadow length) to the hypotenuse (pole length $b$): $$\cos(54^\circ) = \frac{\text{shadow length}}{\text{pole length}} = \frac{21}{b}$$ 5. **Solve for $b$:** $$b = \frac{21}{\cos(54^\circ)}$$ 6. **Calculate $\cos(54^\circ)$:** $$\cos(54^\circ) \approx 0.5878$$ 7. **Calculate $b$:** $$b = \frac{21}{0.5878} \approx 35.74$$ 8. **Round to the nearest foot:** $$b \approx 36$$ **Final answer:** The length of the pole is approximately **36** feet.
b21 ft62°8°