Mammoth Memory

Where can mirror lines go?

Mirror lines can go anywhere.

The mirror line can be placed anywhere just reflect

Where are the mirror lines?

Remember the formula for a straight line is:

`y=mx+c`

(you must see and learn the section on straight lines before you proceed.)

 

Verticle lines

 

Example

Draw a reflection of the following image with a mirror line on `x=3`.

Reflect this image so it mirrors vertically

NOTE:

For `x=3`  we can work out that if:

`y=1`  then `x=3`

`y=2`  then `x=3`

`y=3`  then `x=3`  etc

 

If we plot this on our graph we can find the mirror line.

Draw the mirror line vertically so it goes through the x axis but parallel with the Y axis

We can now complete the reflection.

Complete the reflection through the mirror line

 

Horizontal lines

 

Example

Draw a reflection of the following image with a mirror line on `y=4`.

Reflect this image so it mirrors horizontally

NOTE:

For `y=4`  we can work out that if:

`x=5`  then `y=4`

`x=4`  then `y=4`

`x=3`  then `y=4`  etc

 

If we plot this on our graph we can find the mirror line.

Draw the mirror line through the Y axis so it is parallel with the x axis

We can now complete the reflection.

Complete the reflection through the mirror line

 

Diagonal lines

 

Example 1

Draw a reflection of the following image with a mirror line on `y=x`.

Reflect this image so it mirrors diagonally

NOTE:

For `y=x`  we can work out that if:

`y=1`  then `x=1`

`y=2`  then `x=2`

`y=3`  then `x=3`  etc

 

If we plot this on our graph we can find the mirror line.

Draw a line through the intersection of both axis this is the diagonal mirror line

We can now complete the reflection.

Complete the reflection through the mirror line

 

Example 2

Draw a reflection of the following image with a mirror line `y=-x`.

Reflect this shape diagonally

 

NOTE:

For `y=-x`  we can work out that if:

`y=1`  then `x=-1`         `(1=-1timesx`    therefore   `x=-1)`

`y=2`  then `x=-2`

`y=3`  then `x=-3`  etc

 

If we plot this on our graph we can find the mirror line.

Draw the mirror line through Y -x

We can now complete the reflection.

Complete the reflection through the mirror line

 

 

Other examples

 

Example 1

On the grid below reflect the triangle in the line A, B.

Reflect this image where the mirror line goes through the shape

Redraw as follows:

Measure and reflect through the shape as normal

 

Example 2

Describe the single transformation that maps A to B.

Describe this reflection

You must first describe what this is and it is a REFLECTION.

You must now find the mirror line.

This is easy because we can describe this as a mirror line along the `x` axis.

Or

If you want to get technical, it is the line `y=0`.

i.e. `x=1`  then `y=0`         

      `x=2`  then `y=0`

      `x=3`  then `y=0`  etc

 

Answer:

This is a reflection where the mirror line is on the `x` axis.

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