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Aptitude & Reasoning · B — Logical Reasoning

Direction Sense

Keep north at the top of your page, track every turn, and let Pythagoras handle the 'how far from start' twist.

Test weight: MediumTime / question: 35–55 secDifficulty: Easy → Medium

Direction questions test whether you can follow a path and read the final bearing or the straight-line distance back to the start. Always draw a small compass and plot each leg.

Direction rules

A right turn while facing North points you East; another right faces South (turns are clockwise). Sunrise is in the East, sunset in the West — morning shadows fall West, evening shadows East. For straight-line distance from start, the legs form a right triangle: distance = sqrt(a^2 + b^2).

  • A right turn while facing North points you East; another right faces South (turns are clockwise).
  • Sunrise is in the East, sunset in the West — morning shadows fall West, evening shadows East.
  • For straight-line distance from start, the legs form a right triangle: distance = sqrt(a^2 + b^2).

How to Approach It

  • Draw a compass with north up — Begin each problem with a fresh compass so that left and right are never ambiguous. Plot the starting point and then each leg of the journey in turn.
  • Re-orient after every turn — A turn is always relative to your current facing, not to the page. Update the facing direction before you plot the next leg.
  • Find the net displacement — The straight-line distance back to the start uses the perpendicular legs as a right triangle, so apply Pythagoras — and recognise the 3-4-5 and 5-12-13 triples on sight.
  • Lean on turn-pairs and shadows — Two turns the same way reverse your facing, and morning shadows fall west while evening shadows fall east. These give instant answers to facing questions.

Techniques & Methods

  • Compass on the page — Keep north up and redraw your facing after every turn.
  • Turns in pairs reverse — Two right turns (or two left turns) flip your facing by 180°.
  • Pythagoras for displacement — Perpendicular legs give a right triangle; know 3-4-5 and 5-12-13. e.g. 6 km N, 8 km E → 10 km from start.
  • Shadow rule — Morning shadows fall west; evening shadows fall east.
The Edge
When the path goes North then East (or any two perpendicular legs), the displacement is the hypotenuse. Memorise the 3-4-5 and 5-12-13 triples — most questions are built on them. Two right turns reverse your facing; two left turns do the same. Count turns in pairs to fast-track the final direction.
Worked example
A person walks 3 km north, then 4 km east. How far is she from the start?
  1. Sketch it: she goes 3 km north, then turns and goes 4 km east, and north and east meet at a right angle.
  2. The straight-line distance back to the start is the hypotenuse of a right triangle with legs 3 and 4.
  3. Apply Pythagoras: distance = sqrt(3² + 4²) = sqrt(9 + 16) = sqrt(25).
  4. sqrt(25) = 5, so she is 5 km from the start. (This is the familiar 3-4-5 triangle.)
Worked example
Facing north, a man turns right, then right again. Which way does he now face?
  1. Start facing north and turn right (clockwise): he now faces east.
  2. Turn right again from east: he now faces south.
  3. A useful check: two right turns add up to 180°, which reverses the original facing.
  4. North reversed is south, confirming the result.

Worked Drills

Worked example
A man walks 12 km north, then 5 km east. His straight-line distance from the start is: (a) 13 km b) 15 km c) 17 km d) 18 km)
  1. The two legs are perpendicular, forming a right triangle with legs 12 and 5.
  2. distance = sqrt(12² + 5²) = sqrt(144 + 25) = sqrt(169).
  3. sqrt(169) = 13 (the 5-12-13 triple).
Worked example
From a point, a person goes 4 km west, then 3 km north, then 4 km east. He is now: (a) 3 km North of start b) 5 km NE c) 4 km East d) 7 km away)
  1. The 4 km west and 4 km east cancel exactly.
  2. Only the 3 km north remains.
  3. So he is 3 km north of the start.
Worked example
A starts and walks 6 km east; B starts from the same point and walks 8 km north. The distance between them is: (a) 8 km b) 10 km c) 12 km d) 14 km)
  1. Their paths are perpendicular (east vs north).
  2. Distance between = sqrt(6² + 8²) = sqrt(36 + 64) = sqrt(100).
  3. sqrt(100) = 10.
Worked example
In the morning, a man walks directly towards his own shadow. He is moving towards the: (a) East b) West c) North d) South)
  1. In the morning the sun is in the east, so shadows fall toward the west.
  2. Walking toward his own shadow means walking west.
Worked example
A man walks 1 km north, 1 km east, 1 km north, 1 km east. His overall direction from the start is: (a) North-East b) North-West c) South-East d) South-West)
  1. Add the north legs: 1 + 1 = 2 km north.
  2. Add the east legs: 1 + 1 = 2 km east.
  3. Equal north and east displacement points north-east.
Worked example
Facing south, a man turns left, walks, then turns left again. He now faces: (a) North b) South c) East d) West)
  1. Facing south, a left turn points him east.
  2. A second left turn from east points him north.
Worked example
Walk 9 km west then 12 km south. Distance from start: (a) 13 km b) 15 km c) 17 km d) 21 km)
  1. West and south are perpendicular legs.
  2. distance = sqrt(9² + 12²) = sqrt(81 + 144) = sqrt(225).
  3. sqrt(225) = 15.
⚠ Watch out
  • "Right" and "left" are relative to the current facing, not the page.
  • Net displacement is the straight line, not the total distance walked.
  • Re-orient your compass after every turn before plotting the next leg.
Takeaways
  • Draw a fresh compass with north up for every problem.
  • Update your facing after each turn before plotting the next leg.
  • Straight-line distance is Pythagoras — memorise 3-4-5 and 5-12-13.
  • Two same-direction turns reverse your facing; opposite legs cancel.
Practice this — take a timed mock →
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