1. **State the problem:** We have a lighthouse of height $h$ and two points $A$ and $B$ on the horizontal line from the base of the lighthouse. The horizontal distance from $A$ to the lighthouse base is 1315 feet. The angle of elevation from $A$ to the top of the lighthouse is $12^\circ$, and from $B$ it is $8^\circ$. We need to find the distance from $A$ to $B$.
2. **Identify known values and variables:**
- Height of lighthouse: $h$ (unknown)
- Distance from $A$ to lighthouse base: $1315$ ft
- Distance from $B$ to lighthouse base: $x$ ft (unknown)
- Angle of elevation at $A$: $12^\circ$
- Angle of elevation at $B$: $8^\circ$
3. **Use the tangent function:**
The tangent of the angle of elevation equals the opposite side (height $h$) over the adjacent side (horizontal distance).
From point $A$:
$$\tan(12^\circ) = \frac{h}{1315} \implies h = 1315 \tan(12^\circ)$$
From point $B$:
$$\tan(8^\circ) = \frac{h}{x} \implies h = x \tan(8^\circ)$$
4. **Set the two expressions for $h$ equal:**
$$1315 \tan(12^\circ) = x \tan(8^\circ)$$
5. **Solve for $x$:**
$$x = \frac{1315 \tan(12^\circ)}{\tan(8^\circ)}$$
6. **Calculate $x$ using approximate tangent values:**
$$\tan(12^\circ) \approx 0.2126, \quad \tan(8^\circ) \approx 0.1405$$
$$x = \frac{1315 \times 0.2126}{0.1405} \approx \frac{279.4}{0.1405} \approx 1987.9 \text{ feet}$$
7. **Find the distance from $A$ to $B$:**
Since $A$ is 1315 feet from the lighthouse and $B$ is $x \approx 1987.9$ feet from the lighthouse, and $B$ lies between $A$ and the lighthouse, the distance from $A$ to $B$ is:
$$|1987.9 - 1315| = 672.9 \approx 673 \text{ feet}$$
**Final answer:** The distance from point $A$ to point $B$ is approximately **673 feet**.
Lighthouse Distance A74Aab
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