Total Walking Time
1. **State the problem:**
Melur walks along the path A to B, then B to C, then C to A. We know distances AB = 3.6 km, AC = 8.4 km, and bearings: B from A is 054°, C from B is 132°. We need to find the total time taken walking at 6 km/h.
2. **Find length BC:**
We have triangle ABC with sides AB = 3.6 km, AC = 8.4 km, and need BC.
3. **Find angle at B:**
Bearing of B from A is 054°, so line AB makes 54° from north.
Bearing of C from B is 132°, so line BC makes 132° from north.
The angle ABC is the difference between these bearings:
$$\angle ABC = 132^\circ - 54^\circ = 78^\circ$$
4. **Use Law of Cosines to find BC:**
$$BC^2 = AB^2 + AC^2 - 2 \times AB \times AC \times \cos(\angle ABC)$$
$$BC^2 = 3.6^2 + 8.4^2 - 2 \times 3.6 \times 8.4 \times \cos(78^\circ)$$
Calculate each term:
$$3.6^2 = 12.96$$
$$8.4^2 = 70.56$$
$$\cos(78^\circ) \approx 0.2079$$
So,
$$BC^2 = 12.96 + 70.56 - 2 \times 3.6 \times 8.4 \times 0.2079$$
$$BC^2 = 83.52 - 12.57 = 70.95$$
$$BC = \sqrt{70.95} \approx 8.42 \text{ km}$$
5. **Calculate total distance walked:**
$$\text{Total distance} = AB + BC + CA = 3.6 + 8.42 + 8.4 = 20.42 \text{ km}$$
6. **Calculate total time:**
Speed = 6 km/h
$$\text{Time} = \frac{\text{Distance}}{\text{Speed}} = \frac{20.42}{6} \approx 3.403 \text{ hours}$$
7. **Convert time to hours and minutes:**
$$0.403 \times 60 = 24.18 \text{ minutes}$$
So, total time is approximately 3 hours 24 minutes.
**Final answer:** Melur takes about **3 hours 24 minutes** to complete the walk.