What does perpendicular to mean? [closed]

I am reading a math books and i cant understand this

the xz plane is perpendicular to the y-axis, and the yz plane is perpendicular to the x-axis.

On googling perpendicular means two lines intersect to form a 90 degree angle.

SO in my understanding if im right. does that mean that x and z axis intersects to y axis to form 90 degree and y and z axis intersects to x axis?

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closed as off-topic by Bradd Szonye, tchrist, RegDwigнt♦Apr 6 '14 at 2:19

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "Questions that can be answered using commonly-available references are off-topic. A list of these references can be found here: List of general references" – RegDwigнt
If this question can be reworded to fit the rules in the help center, please edit the question.

This question appears to be off-topic because it is about mathematics. – Bradd Szonye Apr 6 '14 at 1:38
@Bradd But it is still explained in english.. – Tifa Apr 6 '14 at 1:40
Should be closed. Any dictionary will provide the answer immediately. – Vector Apr 6 '14 at 1:47
Please dont. I dont understand those meaning and im looking for a confirmation. Is it that hard to just comment the answer than to close? – Tifa Apr 6 '14 at 1:48

"the xz plane is perpendicular to the y-axis, and the yz plane is perpendicular to the x-axis"

We are given a three axis model of space; the three axis are each perpendicular to the other (imagine looking at a corner of a cube, you see three lines intersecting at the corner - those three lines are perpendicular to each other).

The xz plane is the infinite flat space (ie plane) that is on both x and z axis. Since each of those axis is perpendicular to the y-axis, the xz plane is perpendicular to the y-axis as well. Similarly the yz plan is perpendicular to the x-axis.

To see this visually take your cube and pick a corner, on each of the three lines (ie edges) that forms the corner assign one of the labels x, y, or z. Now you can see that the plane defined by the lines x and z (the xz plane) is in fact perpendicular to the line labeled y.

Your understand is right but you leave out enough to leave it unclear to the reader if you actually understand it :) Since you are asking one must assume you might not. Hopefully this answer crystalizes your understanding one way or the other. IMO this question fits better in math.SE.

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Two lines are perpendicular if they intersect at a 90 degree angle; for example, the lines labeled `x` and `y` below -

EDIT

To add `z` make a third line perpendicular to `x` and `y` (note: this is now 3 dimensions represented in 2),

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so my assumptions are right then? xy perpendicular to z means x and y intersects to z? – Tifa Apr 6 '14 at 1:46
@Tifa Edited. Note that `z` introduces a third dimension, math adds dimensions like candy sometimes. – Elliott Frisch Apr 6 '14 at 1:50
@Tifa your statement is somewhat ambiguous. – Ram Apr 6 '14 at 2:07