Reflections Flashcards

All 6 cards in this deck

What must you state to fully describe a reflection?

The word "reflection" and the equation of the mirror line.
e.g. reflection in the line $y = 3$

What is the equation of the $x$-axis when it is used as a mirror line?

$y = 0$

What are the steps to reflect a shape in a given mirror line?
e.g. reflect in the line $y = 3$

1. Draw the mirror line $y = 3$.
2. Measure each vertex's perpendicular distance to the line, e.g. a vertex 2 above it.
3. Mark the image vertex the same distance on the other side (2 below) and join up.

Where does the mirror line $y = x$ lie on a coordinate grid?

A diagonal line through the origin sloping upwards at $45^\circ$, through all points whose $x$ and $y$ coordinates are equal.

True or false? A point that lies on the mirror line stays in the same place after a reflection.

True.
Its distance from the mirror line is zero, so the image point is on top of it.

True or false? A reflection keeps the orientation of the shape the same.

False.
The image is flipped (orientation reversed), though it is still congruent to the object.