Performing Reflections

This activity involves the use of tools to plot points and draw lines. If you are not sure how to do that on Geogebra, watch this video. Note that you can also use the delete button on your keyboard to erase mistakes.
Reflection in a Vertical Line
The first type of reflection is on a vertical line. The most common of these is the y-axis, though you may be asked to reflect a shape in any vertical lines. [br][br]These lines will have the equation x=a, where a is the value of the point where the line passes the x-axis. The y-axis has the equation x=0 as it passes through the x-axis at 0.[br][br]Use the applet to visualise how a reflection changes if the mirror line is moved. Use the slider to move the line left and right. It starts on x=0. Try moving the points of the red triangle (or click on the shape area to move the whole shape) to see how the other changes as well.
Reflection in the line x=a
What happens when one shape is moved closer to the mirror line?
What happens when one shape is moved closer to the mirror line?
What happens when the mirror line cuts through one of the shapes?
Are the shapes always the same distance away from the mirror line?
Reflect the quadrilateral in the y-axis
State the coordinates of the new quadrilateral.
What type of quadrilateral is the shape?
Reflect in the line x=-3
State the coordinates of the new quadrilateral.
What type of quadrilateral is the new shape?
Reflection in a Horizontal Line
The second type of reflection is on a horizontal line. The most common of these is the x-axis, though you may be asked to reflect a shape in any horizontal lines. [br][br]These lines will have the equation y=a, where a is the value of the point where the line passes the y-axis. The x-axis has the equation y=0 as it passes through the y-axis at 0.[br][br]Use the applet to visualise how a reflection changes if the mirror line is moved. Use the slider to move the line up and down. It starts on y=0. Try moving the points of the purple quadrilateral (or click on the shape area to move the whole shape) to see how the other changes as well.
Reflection in the line x=a
Reflect the triangle in the x-axis
State the coordinates of the new triangle.
What type of triangle is the shape?
Reflect the quadrilateral in the line y=7
State the coordinates of the new quadrilateral.
Reflect the quadrilateral in the line y=7
What type of quadrilateral is the shape?
Reflection in a Diagonal Line
Reflection in the line y=x
The final type of reflection is on a diagonal line. You will be asked to reflect in the line y=x or y=-x.[br][br]Use the applet to visualise how a reflection changes if the points on the shape are moved. The first example shows a reflection in the line y=x. The second example is a reflection in the line y=-x.[br][br]Try moving the points of the green shape (or click on the shape area to move the whole shape) to see how the other changes as well.
Reflection in the line y=-x
Reflect the triangle in the line y=x
State the coordinates of the new triangle.
What type of triangle is the shape?
Reflect the triangle in the line y=-x
State the coordinates of the new triangle.
[size=200]For the next few questions, you will be given the equation of the mirror line. Draw the line for each question, then reflect the shape.[/size]
Reflect in the line y=-1
Reflect in the line x=4
Reflect in the y-axis, then reflect the new shape in the x-axis
Reflect in the line y=x
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Information: Performing Reflections