11 Plus Exams Forum

The question is

Write the new co-ordinates if each of these points is reflected in the y axis.

q1 : (1,1) ____
q2 : (2,1) ____
q3 : (0,3) ____
q4 : (3,2) ____
q5 : (1,0) ____

Thanks for your help.

Have you tried drawing them out ? can be easier to see the coordinates on the actual graph.

A maths teacher does not do someone's maths homework!

Draw a diagram and, as it says, use the y axis as the mirror.

In case you just aren't familiar with co-ordinates:
:: the first figure is the position on the X-axis (the horizontal one)
:: the second figure is the position on the Y-axis (the vertical one)
:: they are always presented as (X,Y) - easy to remember if you think that you have to go along to your mountain before you climb up it!

So your first example (1,1) means go along 1, then up 1. If this is "reflected in the Y axis" this means go left (backwards) instead of right (forwards) (or vice versa if your original co-ordinate was a negative). So go left 1, then up 1 - i.e (-1,1). The others will follow the same pattern.

"Reflected in the X axis" would mean that the second co-ordinate would be the negative of the orginal.

It gets a little more complicated when the reflection is in a line other than an axis.

No it wouldn't. Try it with a mirror and have a look.

If you put the mirror on the y axis, it is the x coordinate that changes. I don't want to tread on toes and do it for you, but I don't want you to get it wrong. Try it on a piece of paper and it should be much easier to picture.

Reflected in the y axis means the vertical axis (put a mirror along the y axis and have a look) so the y coordinate will stay the same and the x coordinate will change.

Reflected in the x axis means the horizontal axis so the x coordinate will stay the same and the y coordinate will change.

This is true for all horizontal and vertical lines, not just the axes.

Moved - that's not exactly correct as some points will remain where they are under a reflection ....

Thanks everyone for your lovely help.