mpt · CSS study notes
Direction & Distance
Core Formulas
- Standard compass: N, S, E, W (and NE, NW, SE, SW between them)
- Right turn from facing North → now facing East; Left turn from North → now facing West (rotate the compass 90° in the turn direction)
- Shortest/final distance from start (not total path walked) uses the straight-line (resultant) distance:
where x and y are the net displacement along two perpendicular axes
Turn Rules Quick Reference
- Facing North: Right turn → East; Left turn → West
- Facing East: Right turn → South; Left turn → North
- Facing South: Right turn → West; Left turn → East
- Facing West: Right turn → North; Left turn → South
- A 180° turn (either direction) always means facing the exact opposite direction
Worked Examples
- Walk 3 km North, then 4 km East → shortest distance back:
- Walk 6 km South, then 8 km West → shortest distance to start:
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A man walks 5 km North, turns right, walks 5 km, turns right again, walks 5 km. What direction is he from the start, and how far?
→ North 5km → turn right (facing East) walk 5km → turn right (facing South) walk 5km → the N and S legs cancel → he is 5 km East of start
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Facing North, a person turns 90° clockwise, then 180°, then 90° anticlockwise. Which direction do they face now?
→ North → (90° CW) East → (180°) West → (90° CCW) South
Drill
- Walk 12 km East, then 5 km North. Shortest distance to start? — 13 km (5-12-13 triple)
- Facing South, turn left twice (90° each). Which direction now? — North
- A person walks 4km North, 3km East, 4km South. Final position relative to start? — 3 km East
- Facing East, turn right, then right again. Which direction? — West
- Walk 8km North, 6km East, 8km South, 6km West. Distance from start? — 0 km (back at start)
Practice tracker
YYYY-MM-DD
- Attempted/Correct:
- Mistake pattern: