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Question

Rohan walks a distance of 3 kms towards North, then turns to his left and walks for 2 kms. He again turns left and walks 3 kms. At this point he turns to his left and walks for 3 kms. How many kms is he from the starting point?

The correct answer is
1

Solving Rohan's Directional Walk Problem

This problem involves tracking a person's movement through different directions and calculating their final distance from the starting point. Let's break down Rohan's journey step by step.

Tracking Rohan's Path

We can visualize Rohan's path or use coordinates to find his final position relative to his start.

  • Step 1: Northward Movement

    Rohan starts at a point (let's call it the origin) and walks 3 kms towards North. His position is now 3 kms North of the start.

  • Step 2: First Left Turn (Westward)

    He turns to his left. Since he was facing North, his left is West. He walks 2 kms West. His position is now 3 kms North and 2 kms West of the start.

  • Step 3: Second Left Turn (Southward)

    He again turns left. Now facing West, his left is South. He walks 3 kms South. This movement cancels out his initial 3 kms Northward movement. He is now on the same horizontal line as his starting point, but 2 kms West of it.

  • Step 4: Third Left Turn (Eastward)

    He turns left again. Facing South, his left is East. He walks for 3 kms. Starting from 2 kms West of the origin, walking 3 kms East means he first covers the 2 kms back to the starting point's North-South line, and then continues another 1 km East.

Calculating Final Distance from Start

After the final step, Rohan is 1 km East of the North-South line passing through his starting point. Since his North-South displacement is zero (3 km North - 3 km South = 0 km), his final position is exactly 1 km East of his starting point.

Therefore, the distance from the starting point is simply this eastward displacement.

Final Distance = 1 km

Using Coordinates (Alternative Method)

Let the starting point be (0, 0).

  • After walking 3 km North: Position is (0, 3).
  • Turning left (West) and walking 2 km: Position is (-2, 3).
  • Turning left (South) and walking 3 km: Position is (-2, 3 - 3) = (-2, 0).
  • Turning left (East) and walking 3 km: Position is (-2 + 3, 0) = (1, 0).

The starting point is (0, 0) and the final point is (1, 0).

The distance using the distance formula:

Distance = $\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$

Distance = $\sqrt{(1 - 0)^2 + (0 - 0)^2}$

Distance = $\sqrt{1^2 + 0^2}$

Distance = $\sqrt{1}$

Distance = $1$ km.

Both methods confirm that Rohan is 1 km away from his starting point.

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Important Questions from Direction and Distance

  1. Johny starts from Point A and drives 6 km towards the North. He then takes a right turn, drives 17 km, turns right and drives 13 km. He then takes a right turn and drives 8 km. He takes a final right turn, drives 7 km and stops at Point P. How far (shortest distance) and towards which direction should he drive to reach Point A again? (All turns are 90 degrees turns only unless specified.)
  2. Town Q is to the east of Town P. Town R is to the south of Town Q. Town S is to the east of Town R. Town T is to the south of Town S. Town U is to the east of Town T. What is the position of Town U with respect to Town Q?
  3. Binoy starts from Point Y and drives 16 km towards the north. He then takes a right turn and drives 43 km, then turns right and drives 38 km. He then takes a right turn and drives 19 km. He takes a final right turn, drives 22 km and stops at Point Z. How far (shortest distance) and in which direction should he drive in order to reach Point Y again? (All turns are 90-degree turns only unless specified.)
  4. Himank starts from Point A and drives 13 km towards West. He then takes a left turn, drives 3 km, turns left and drives 16 km. He then takes a left turn and drives 6 km. He takes a final left turn, drives 3 km and stops at Point P. How far (shortest distance) and towards which direction should he drive in order to reach Point A again? (All turns are 90° turns only unless specified.)
  5. Shyam starts from Point A and drives 12 km towards east. He then takes a right turn,
    drives 7 km, turns right and drives 5 km. He then takes a left turn and drives 9 km. He
    takes a final right turn, drives 7 km and stops at Point P. How far (shortest distance) and
    towards which direction should he drive in order to reach Point A again? (All turns are
    $90^{\circ}$ turns only unless specified.)
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