00:03
Okay, in this problem, we're asked to find which of these shapes have rotational symmetry.
00:10
So what it means to have rotational symmetry is that if i have a shape, let's just say we have the shape, the letter i, right? if i rotate this shape, right? let's just say i rotated 90 degrees, then my shape would look like this, right? and then if i rotated another 90 degrees, then the shape would look like this.
00:27
So notice that when i flip this 180 degrees, when i rotated 180 degrees, and i rotated 180.
00:32
80 degrees.
00:33
My ending shape looks exactly like my beginning shape.
00:37
All right.
00:37
So that's what it means to have rotational symmetry.
00:39
If i rotate it less than a full circle and i end up getting the same shape back, then it has rotational symmetry.
00:46
Okay.
00:47
So let's look at this one.
00:48
The one that has the four arrows.
00:50
I'm not going to draw it...