1. **Problem statement:**
A rescue boat travels from the harbor to Area A on a bearing of 070° for 40 km, then from Area A to Area B on a bearing of 150° for 55 km.
We need to find:
- The bearing of Area A from Area B.
- How far east Area B is from Area A.
- The direct distance from the harbor to Area B.
2. **Formulas and rules:**
- Bearings are measured clockwise from north.
- To find coordinates from bearings and distances, use:
$$x = d \times \sin(\theta)$$
$$y = d \times \cos(\theta)$$
where $\theta$ is the bearing angle.
- To find the bearing from one point to another, calculate the angle of the vector connecting them relative to north.
- Distance between two points $(x_1,y_1)$ and $(x_2,y_2)$ is:
$$\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$$
3. **Calculate coordinates:**
- Harbor at origin: $(0,0)$
- Area A:
$$x_A = 40 \times \sin(70^\circ) = 40 \times 0.9397 = 37.59$$
$$y_A = 40 \times \cos(70^\circ) = 40 \times 0.3420 = 13.68$$
- Area B from Area A:
$$x_B = x_A + 55 \times \sin(150^\circ) = 37.59 + 55 \times 0.5 = 37.59 + 27.5 = 65.09$$
$$y_B = y_A + 55 \times \cos(150^\circ) = 13.68 + 55 \times (-0.8660) = 13.68 - 47.63 = -33.95$$
4. **Bearing of Area A from Area B:**
- Vector from B to A:
$$\Delta x = x_A - x_B = 37.59 - 65.09 = -27.5$$
$$\Delta y = y_A - y_B = 13.68 - (-33.95) = 47.63$$
- Angle from north:
$$\theta = \arctan\left(\frac{|\Delta x|}{\Delta y}\right) = \arctan\left(\frac{27.5}{47.63}\right) = 30^\circ$$
- Since $\Delta x$ is negative and $\Delta y$ positive, vector points northwest quadrant, so bearing is:
$$360^\circ - 30^\circ = 330^\circ$$
5. **East distance from Area A to Area B:**
- East distance is difference in $x$ coordinates:
$$x_B - x_A = 65.09 - 37.59 = 27.5 \text{ km}$$
6. **Direct distance from harbor to Area B:**
$$d = \sqrt{(65.09)^2 + (-33.95)^2} = \sqrt{4236.7 + 1152.2} = \sqrt{5388.9} = 73.43 \text{ km}$$
**Final answers:**
- Bearing of Area A from Area B: $330^\circ$
- East distance from Area A to Area B: 27.5 km
- Direct distance from harbor to Area B: 73.43 km
Rescue Boat 879102
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