00:01
All right, so it says, do problem 10 for a rectangle.
00:03
That means finding the symmetry groups of a rectangle.
00:09
And label the vertices 1, 2, 3, and 4.
00:15
So i notice that we can reflect across the x -axis here.
00:25
So that's going to put 1 here, 4, 3, and 2.
00:32
Oh, excuse me, 2 and that's what it is already.
00:35
3 should be up here.
00:37
2 should be up here.
00:40
Let's get that going there.
00:43
We can also reflect across the y -axis.
00:49
So this is 2, 3.
00:54
This is 1 and 4.
01:01
Or we can, of course, do them both.
01:05
Great.
01:08
And then if we reflect across the vertical axis here, 3 and 4 will switch sides.
01:15
3, 4.
01:17
And then these guys will switch sides.
01:19
This becomes 2 and 3.
01:25
That seems right.
01:26
No, that's not quite right.
01:31
Excuse me.
01:32
So here, we're reflecting this across the vertical axis, which means 3 and 2 are here.
01:39
4 and 1 are here, which also is the same as if we take this and flip it across the horizontal axis.
01:45
1 and 4 switch vertically.
01:46
3 and 2 switch vertically...