Let Us Make a Windmill Firki — Rotational Symmetry (p. 137)
Observe the dot in the firki. Does the firki look the same after 1/4, 1/2, 3/4, and a full turn?
A firki (windmill) has 4 blades arranged equally around the centre.
When you turn it by 1/4 turn (90 degrees), one blade moves to where the next blade was — the firki looks exactly the same.
This is true for every 1/4 turn: after 1/4, 2/4 (= 1/2), 3/4, and a full (4/4) turn, the firki looks the same.
The dot on the blade helps you track how far it has turned, but the overall shape (all 4 blades) looks identical at each of these positions.
So: Yes, the firki looks the same after 1/4 turn, 1/2 turn, 3/4 turn, and a full turn.
Answer: Yes. The firki looks the same after every 1/4 turn (at 1/4, 1/2, 3/4, and full turn) because it has 4 equal blades.
