Two ships, A and B, leave a port at 11:00.

- A travels on a bearing of [tex]080^{\circ}[/tex] at a speed of [tex]25 \, \text{km/h}[/tex].
- B travels on a bearing of [tex]152^{\circ}[/tex] at a speed of [tex]20 \, \text{km/h}[/tex].

(a) Work out the distance between A and B at 14:00.



Answer :

Sure, let's break down the problem step by step to determine the distance between the two ships, A and B, at 14:00.

### Step 1: Determine the time traveled
Both ships travel from 11:00 to 14:00, which is a total of 3 hours.

### Step 2: Calculate distances traveled by each ship
- Ship A travels at a speed of 25 km/h:
[tex]\[ \text{Distance traveled by A} = 25 \text{ km/h} \times 3 \text{ hours} = 75 \text{ km} \][/tex]

- Ship B travels at a speed of 20 km/h:
[tex]\[ \text{Distance traveled by B} = 20 \text{ km/h} \times 3 \text{ hours} = 60 \text{ km} \][/tex]

### Step 3: Convert bearings to coordinates
To find the position of each ship, we use trigonometry. Bearings are provided in degrees and need to be converted to coordinates.

For Ship A (bearing of [tex]\( 080^\circ \)[/tex]):
- x-coordinate of A:
[tex]\[ x_A = 75 \times \sin(80^\circ) \approx 73.86 \text{ km} \][/tex]

- y-coordinate of A:
[tex]\[ y_A = 75 \times \cos(80^\circ) \approx 13.02 \text{ km} \][/tex]

For Ship B (bearing of [tex]\( 152^\circ \)[/tex]):
- x-coordinate of B:
[tex]\[ x_B = 60 \times \sin(152^\circ) \approx 28.17 \text{ km} \][/tex]

- y-coordinate of B:
[tex]\[ y_B = 60 \times \cos(152^\circ) \approx -52.98 \text{ km} \][/tex]

### Step 4: Calculate the distance between the coordinates
Now, we use the distance formula between the coordinates [tex]\((x_A, y_A)\)[/tex] and [tex]\((x_B, y_B)\)[/tex]:

[tex]\[ \text{Distance between ships} = \sqrt{(x_B - x_A)^2 + (y_B - y_A)^2} \][/tex]

Substituting the calculated values:
[tex]\[ \text{Distance} = \sqrt{(28.17 - 73.86)^2 + (-52.98 - 13.02)^2} \][/tex]

Solving this:
[tex]\[ \text{Distance} = \sqrt{(-45.69)^2 + (-66.00)^2} \][/tex]
[tex]\[ \text{Distance} \approx \sqrt{2087.28 + 4356.00} \][/tex]
[tex]\[ \text{Distance} \approx \sqrt{6443.28} \][/tex]
[tex]\[ \text{Distance} \approx 80.27 \text{ km} \][/tex]

Thus, the distance between ships A and B at 14:00 is approximately 80.27 km.