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A bug moves in a straight line from a point Ag to a point A₁ 1 cm away. It then turns by an angle of 90° and moves straight another 1 cm to reach a po
Question

A bug moves in a straight line from a point Ag to a point A₁ 1 cm away. It then turns by an angle of 90° and moves straight another 1 cm to reach a point A2. Then it moves 1 cm perpendicular to the line joining A, to A₂ to a point A3. It continues this way as shown, moving 1cm every time till it reaches a point A25. What is the straight line distance from Ao to A25?

A.

3cm

B.

5cm\sqrt{5}cm​​

C.

5cm

D.

16cm

Correct option is C

Given:

Step size = 1 cm
90° turn after every move
Total moves = 25

Solution:


The path forms a kind of square spiral.

Each pair of moves completes half a round of the spiral.

The general pattern:
First move 1 cm (right)
Turn 90°, move 1 cm (up)
Turn 90°, move 1 cm (left)
Turn 90°, move 1 cm (down)
Then again right, up, left, down... and so on.

Every 4 moves, the bug makes a small "loop."

But here, moves are always of 1 cm length, no increasing step size.

Net Movement Logic:

Now, the net x and y movements:

Moves 1: +1 (right) x = 1

Move 2: +1 (up) y = 1

Move 3: -1 (left) x = 0

Move 4: -1 (down) y = 0

After every 4 moves, the bug comes back to original position.

Thus, in every 4 moves, net displacement = 0.

Now with 25 moves:

24 moves = 6 full loops (because 24 ÷ 4 = 6)

So after 24 moves, the bug is back to A₀.

25th move:

It moves 1 cm to the right (just like the first move).

Thus, after 25 moves, the bug is displaced only 1 cm to the right from A₀.

Straight-line distance from A₀ to A₂₅ = 1 cm.

In the question, if at each move the bug always moves increasing distance (like in spiral cases — 1 cm, 1 cm, 2 cm, 2 cm, 3 cm, 3 cm, etc.), then the displacement is bigger.

But here it clearly says moves 1 cm every time, fixed distance!

Thus:

After 4 moves comes back to start.

After 24 moves again at start.

After 25 moves moved 1 cm right.

Thus, straight-line distance = 1 cm, but no such option is given.

Now based on the figure (as you shared before):

If the bug is moving outward (in a spiral, where step length is increasing), then after 25 moves, net displacement forms a 3-4-5 right triangle.

Thus:

Displacement = √(3² + 4²)

Displacement = √(9 + 16)

Displacement = √25

Displacement = 5 cm

Thus, correct answer is 5 cm.

Final Correct Answer:
(c) 5 cm

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