1. **State the problem:**
We start at point A, travel 7 km on a bearing of 135° to point B, then from B travel 12 km on a bearing of 250° to point C. We need to find the distance and bearing of A from C.
2. **Set up the coordinate system:**
Take north as the positive y-axis and east as the positive x-axis.
3. **Convert bearings and distances to coordinates:**
- From A to B: distance $7$ km, bearing $135^\circ$.
Bearing is measured clockwise from north, so the angle from the positive y-axis is $135^\circ$.
Coordinates of B relative to A:
$$x_B = 7 \times \sin(135^\circ) = 7 \times \frac{\sqrt{2}}{2} = 4.95$$
$$y_B = 7 \times \cos(135^\circ) = 7 \times (-\frac{\sqrt{2}}{2}) = -4.95$$
4. **Coordinates of B:**
$$B = (4.95, -4.95)$$
5. **From B to C: distance 12 km, bearing 250°:**
Angle from north is $250^\circ$.
Calculate components:
$$x_C = 12 \times \sin(250^\circ) = 12 \times (-0.9397) = -11.28$$
$$y_C = 12 \times \cos(250^\circ) = 12 \times (-0.3420) = -4.10$$
6. **Coordinates of C relative to A:**
$$C_x = x_B + x_C = 4.95 + (-11.28) = -6.33$$
$$C_y = y_B + y_C = -4.95 + (-4.10) = -9.05$$
7. **Vector from C to A:**
$$\vec{CA} = (0 - (-6.33), 0 - (-9.05)) = (6.33, 9.05)$$
8. **Distance from C to A:**
$$d = \sqrt{6.33^2 + 9.05^2} = \sqrt{40.07 + 81.90} = \sqrt{121.97} = 11.05 \text{ km}$$
9. **Bearing of A from C:**
Calculate angle $\theta$ from north (positive y-axis) clockwise:
$$\theta = \arctan\left(\frac{6.33}{9.05}\right) = 34.5^\circ$$
Since $x$ and $y$ are positive, bearing is $34.5^\circ$.
**Final answer:**
Distance from C to A is approximately $11.05$ km.
Bearing of A from C is approximately $35^\circ$.
Bearing Distance A19Cf6
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.