P, Q, and R are three points on a field. Philip walked 50 m from P to Q on a bearing of 070°. He then walked 80 m from Q to R on a bearing of 120°. Finally, he walked from R to P. How far did he walk altogether?



Answer :

To determine how far Philip walked altogether, we first need to break down the journey into individual legs and then calculate the total distance.

1. Distance Walked from P to Q:
Philip starts at point P and walks 50 meters to point Q on a bearing of 070°.
Therefore, the distance [tex]\( PQ \)[/tex] is 50 meters.

2. Distance Walked from Q to R:
From Q, Philip continues to walk 80 meters to point R on a bearing of 120°.
Thus, the distance [tex]\( QR \)[/tex] is 80 meters.

3. Calculating Coordinates of Point Q:
- The bearing of 070° means that point Q is positioned at an angle of 70° from the North.
- Breaking this down into x and y coordinates using trigonometry:
[tex]\[ x_Q = 50 \times \sin(70°) \][/tex]
[tex]\[ y_Q = 50 \times \cos(70°) \][/tex]

4. Calculating Coordinates of Point R:
- From point Q, moving towards R on a bearing of 120° means this is at [tex]\(120° - 70° = 50°\)[/tex] from the line PQ.
- We calculate the new coordinates:
[tex]\[ x_R = x_Q + (80 \times \sin(120°)) \][/tex]
[tex]\[ y_R = y_Q + (80 \times \cos(120°)) \][/tex]

5. Distance Walked from R to P:
- Having the coordinates of R, we can compute the straight-line distance from R back to P. This is done using the Pythagorean theorem:
[tex]\[ RP = \sqrt{x_R^2 + y_R^2} \][/tex]

6. Total Distance Walked:
- Finally, to find the total distance Philip walked, we sum up the distances PQ, QR, and RP:
[tex]\[ \text{Total distance} = PQ + QR + RP \][/tex]

From our calculations, we find the following distances:
- [tex]\( PQ = 50 \)[/tex] meters
- [tex]\( QR = 80 \)[/tex] meters
- [tex]\( RP \approx 118.50 \)[/tex] meters

Therefore, the total distance that Philip walked is approximately:
[tex]\[ 50 + 80 + 118.50 = 248.50 \text{ meters} \][/tex]

Thus, the total distance Philip walked altogether is approximately 248.50 meters.