Displacement Vector
1. **Problem statement:** We need to find the displacement vector from Winnipeg to Saskatoon given two vectors: Winnipeg to Regina (530 km at 6.9° north of west) and Regina to Saskatoon (230 km at 53° north of west).
2. **Understanding the directions:** "North of west" means we start facing west (which is 180° from east) and rotate northwards by the given angle. So the angles from the positive x-axis (east) are:
- Winnipeg to Regina: $180^\circ - 6.9^\circ = 173.1^\circ$
- Regina to Saskatoon: $180^\circ - 53^\circ = 127^\circ$
3. **Vector components:** We convert each vector into components using:
$$x = r \cos(\theta), \quad y = r \sin(\theta)$$
where $r$ is the magnitude and $\theta$ is the angle from the positive x-axis.
4. **Calculate components for Winnipeg to Regina:**
$$x_1 = 530 \cos(173.1^\circ) = 530 \times \cos(173.1^\circ)$$
$$y_1 = 530 \sin(173.1^\circ) = 530 \times \sin(173.1^\circ)$$
5. **Calculate components for Regina to Saskatoon:**
$$x_2 = 230 \cos(127^\circ) = 230 \times \cos(127^\circ)$$
$$y_2 = 230 \sin(127^\circ) = 230 \times \sin(127^\circ)$$
6. **Sum components to get Winnipeg to Saskatoon displacement:**
$$x = x_1 + x_2$$
$$y = y_1 + y_2$$
7. **Calculate numerical values:**
Using approximate cosine and sine values:
- $\cos(173.1^\circ) \approx -0.993$,
- $\sin(173.1^\circ) \approx 0.120$,
- $\cos(127^\circ) \approx -0.601$,
- $\sin(127^\circ) \approx 0.799$.
Calculate:
$$x_1 = 530 \times (-0.993) = -526.29$$
$$y_1 = 530 \times 0.120 = 63.60$$
$$x_2 = 230 \times (-0.601) = -138.23$$
$$y_2 = 230 \times 0.799 = 183.77$$
Sum:
$$x = -526.29 + (-138.23) = -664.52$$
$$y = 63.60 + 183.77 = 247.37$$
8. **Find magnitude of displacement:**
$$d = \sqrt{x^2 + y^2} = \sqrt{(-664.52)^2 + (247.37)^2}$$
$$d = \sqrt{441572 + 61192} = \sqrt{502764} \approx 709.06 \text{ km}$$
9. **Find direction angle north of west:**
Angle $\phi$ from west towards north is:
$$\phi = \tan^{-1}\left(\frac{y}{-x}\right) = \tan^{-1}\left(\frac{247.37}{664.52}\right)$$
$$\phi \approx \tan^{-1}(0.372) = 20.4^\circ$$
**Final answer:** The displacement of Saskatoon from Winnipeg is approximately 709 km at 20.4° north of west.