1. **State the problem:** We have a lighthouse 111 feet tall and two points A and B on the water. From A, the angle of elevation to the top of the lighthouse is 8°, and from B (closer to the lighthouse), the angle is 16°. We need to find the distance between points A and B.
2. **Set up the variables and diagram:** Let the horizontal distance from point B to the lighthouse base be $x$ feet. Then the distance from point A to the lighthouse base is $x + d$, where $d$ is the distance from A to B that we want to find.
3. **Use the tangent function for right triangles:** The height of the lighthouse is opposite the angle, and the horizontal distance is adjacent.
From point A:
$$\tan(8^\circ) = \frac{111}{x + d}$$
From point B:
$$\tan(16^\circ) = \frac{111}{x}$$
4. **Express $x$ from point B's equation:**
$$x = \frac{111}{\tan(16^\circ)}$$
5. **Express $x + d$ from point A's equation:**
$$x + d = \frac{111}{\tan(8^\circ)}$$
6. **Find $d$ by subtracting:**
$$d = \frac{111}{\tan(8^\circ)} - \frac{111}{\tan(16^\circ)}$$
7. **Calculate the tangent values:**
$$\tan(8^\circ) \approx 0.1405$$
$$\tan(16^\circ) \approx 0.2867$$
8. **Calculate each term:**
$$\frac{111}{0.1405} \approx 790.0$$
$$\frac{111}{0.2867} \approx 387.3$$
9. **Calculate $d$:**
$$d = 790.0 - 387.3 = 402.7$$
10. **Answer:** The distance from point A to point B is approximately **402.7 feet**.
Distance Boat Lighthouse 868Cfe
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