Example Question #1 : Reflections
What is the result of reflecting the point over the y-axis in the coordinate plane?
Reflecting a point
over the y-axis geometrically is the same as negating the x-coordinate of the ordered pair to obtain
Thus, since our initial point was
and we want to reflect it over the y-axis, we obtain the reflection by negating the first term of the ordered pair to get
Example Question #2 : Reflections
How many lines of symmetry does the above figure have?
A line of symmetry of a figure is about which the reflection of the figure is the figure itself. The diagram below shows the only line of symmetry of the figure.
The correct response is one.
Example Question #3 : Reflections
On the coordinate plane, the point is reflected about the -axis. The image is denoted . Give the distance .
The reflection of the point at about the -axis is the point at ; therefore, the image of is . Since these two points have the same -coordinate, the distance between them is the absolute value of the difference between their -coordinates:
Example Question #4 : Reflections
Consider regular Hexagon ; let and be the midpoints of and . Reflect the hexagon about , then again about . Which of the following clockwise rotations about the center would result in each point being its own image under this series of transformations?
Refer to the figure below, which shows the reflection of the given hexagon about ; we will call the image of , call the image of , and so forth.
Now, refer to the figure below, which shows the reflection of the image about ; we will call the image of , call the image of , and so forth.
Note that the vertices coincide with those of the original hexagon, and that the images of the points are in the same clockwise order as the original points. Since coincides with , coincides with , and so forth, a clockwise rotation of five-sixth of a complete turn - that is, ,
is required to make each point its own image under the three transformations.
Example Question #5 : Reflections
Consider regular Hexagon ; let and be the midpoints of and . Reflect the hexagon about , then again about . With which of the following points does the image of under these reflections coincide?
Refer to the figure below, which shows the reflection of about ; we will call this image .
Note that coincides with . Now, refer to the figure below, which shows the reflection of about ; we will call this image - the final image -
Note that coincides with , making this the correct response.