A reflection occurs when we flip an object or shape across a line. Like a mirror, the object is exactly the same size but everything is in the opposite position. In other words, what was on the left will now be on the right and vice versa.
Have a play with the applet below. You can change the shape, the position of the shape and the direction of the line.
As you play, notice how:
- every point on the object or shape has a matching point on the flipped image
- both shapes are the same distance from the reflection line
Examples
Question 1
Which picture shows a reflection?
Think: Which picture looks like its been flipped- A or B?
Do: In (B), the picture is exactly the same. It has just been slid down. This means it's a translation.
In (A), the alien's spaceship has been flipped upside down! So this is the reflection.
Question 2
This picture is an example of a:
Translation (slide)
AReflection (flip)
BRotation (turn)
CMagnification
D
QUESTION 3
Which image below represents the reflection for the following shape about the vertical mirror line?
A
B
C
QUESTION 4
Which image below represents the reflection for the following shape about the vertical mirror line?
A trapezoid is shaded within a grid of evenly spaced horizontal and vertical lines and is positioned to the right of a vertical mirror line. The longer vertical side of the trapezoid, measuring 3 units, is two square units to the right of the vertical mirror line, and the shorter vertical side, measuring 2 units, is one square unit to the right of the mirror line. The bottom horizontal side, connecting the upper endpoints of the two vertical sides, measures 1 unit. The top side of the trapezoid is slanted upward from left to right, connecting the two vertical sides, and its closest point is one square unit away from the vertical mirror line. A
A trapezoid is shaded within a grid of evenly spaced horizontal and vertical lines and is positioned to the right of a vertical mirror line. The shorter vertical side of the trapezoid, measuring 2 units, is two square units to the right of the vertical mirror line, and the longer vertical side, measuring 3 units, is one square unit to the right of the mirror line. The top horizontal side, connecting the upper endpoints of two vertical vertical sides, measures 1 unit. The bottom side of the trapezoid is slanted downward from right to left, connecting the two vertical sides, and its closest point is one square unit away from the vertical mirror line. B
A trapezoid is shaded within a grid of evenly spaced horizontal and vertical lines and is positioned to the right of a vertical mirror line. The longer vertical side of the trapezoid, measuring 3 units, is two square units to the right of the vertical mirror line, and the shorter vertical side, measuring 2 units, is one square unit to the right of the mirror line. The top horizontal side, connecting the upper endpoints of the two vertical sides, measures 1 unit. The bottom side of the trapezoid is slanted downward from left to right, connecting the two vertical sides, and its closest point is one square unit away from the vertical mirror line.
C
A trapezoid is shaded within a grid of evenly spaced horizontal and vertical lines and is positioned to the right of a vertical mirror line. The shorter vertical side of the trapezoid, measuring 1 unit, is one and a half square units to the right of the vertical mirror line, and the longer vertical side, measuring 1 and a half units, is one square unit to the right of the mirror line. The top horizontal side, connecting the upper endpoints of two vertical vertical sides, measures half a unit. The bottom side of the trapezoid is slanted downward from right to left, connecting the two vertical sides, and its closest point is one square unit away from the vertical mirror line. D