Distance Angle Triangle
1. **Problem statement:**
An aircraft flies from A to B, distance AB = 600 km. Due to bad weather, it detours via C. The line CA makes an angle of 28° 15' with AB, and CA = 500 km.
We need to find:
(a) Distance CB
(b) Angle ACB using the sine rule.
2. **Convert angle to decimal degrees:**
28° 15' = 28 + 15/60 = 28.25°
3. **Visualize the triangle:**
Points A, B, and C form a triangle with sides:
- AB = 600 km
- CA = 500 km
- CB = ? (to find)
Angle between CA and AB is 28.25°.
4. **Use the Law of Cosines to find CB:**
$$CB^2 = CA^2 + AB^2 - 2 \times CA \times AB \times \cos(28.25^\circ)$$
Calculate:
$$CB^2 = 500^2 + 600^2 - 2 \times 500 \times 600 \times \cos(28.25^\circ)$$
$$CB^2 = 250000 + 360000 - 600000 \times \cos(28.25^\circ)$$
Calculate \(\cos(28.25^\circ)\): approximately 0.8819
$$CB^2 = 610000 - 600000 \times 0.8819 = 610000 - 529140 = 80860$$
$$CB = \sqrt{80860} \approx 284.3 \text{ km}$$
5. **Use the Law of Sines to find angle ACB:**
Label angles opposite sides:
- Angle at A opposite CB
- Angle at B opposite CA
- Angle at C opposite AB
We know:
- Side AB = 600 km opposite angle C
- Side CA = 500 km opposite angle B
- Side CB = 284.3 km opposite angle A
Using Law of Sines:
$$\frac{\sin(ACB)}{AB} = \frac{\sin(28.25^\circ)}{CB}$$
Solve for \(\sin(ACB)\):
$$\sin(ACB) = \frac{AB}{CB} \times \sin(28.25^\circ) = \frac{600}{284.3} \times \sin(28.25^\circ)$$
Calculate \(\sin(28.25^\circ)\): approximately 0.4735
$$\sin(ACB) = 2.11 \times 0.4735 = 1.0$$
Since sine cannot be more than 1, this means angle ACB is approximately 90°.
6. **Final answers:**
(a) Distance CB is approximately 284.3 km.
(b) Angle ACB is approximately 90°.
This means the triangle is nearly right-angled at C.