Recognize half turns

Detailed Explanation: Recognize half turns

A half turn means turning a shape halfway around a fixed center. It is the same as two quarter turns, or $180^\circ$.

To recognize a half turn:

1. Find the center of the turn.
2. Check that every part of the shape moves to the opposite side of the center.
3. Check that the shape keeps the same size and shape.
4. The shape will look turned upside down, not simply flipped like a mirror.

Example

A triangle is above a dot. Its point faces right.

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After a half turn around the dot:

1. The triangle moves to the opposite side, below the dot.
2. Its point also moves to the opposite direction, so it faces left.
3. The triangle is still the same size and shape.

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   ◀

The triangle has made a half turn because it moved halfway around the center. It did not move only to the side, as it would in a quarter turn, and it was not flipped like a mirror image.