Rotations Flashcards

All 6 cards in this deck

What three things must you state to fully describe a rotation?

The angle, the direction (clockwise or anticlockwise) and the centre of rotation.
e.g. rotation $90^\circ$ clockwise about $(0, 0)$

True or false? A rotation of $180^\circ$ must have its direction stated.

False.
Clockwise and anticlockwise give the same image for $180^\circ$, so no direction is needed.

A rotation of $90^\circ$ anticlockwise is the same as which rotation clockwise?

$270^\circ$ clockwise.

What are the steps to rotate a shape about a given centre using tracing paper?
e.g. rotate $90^\circ$ anticlockwise about $(0, 0)$

1. Trace the shape and mark the centre $(0, 0)$.
2. Hold a pencil point on the centre and turn the paper a quarter turn anticlockwise.
3. Draw the shape in its new position and label it.

What single transformation is the same as a reflection in the $x$-axis followed by a reflection in the $y$-axis?

A rotation of $180^\circ$ about the origin $(0, 0)$.

True or false? A rotation changes the side lengths and angles of a shape.

False.
Lengths and angles are unchanged, so the image is congruent to the object.