My native language is not English and can't realize what does the first sentence on the picture sentence mean. In particular, "each angle and the $x$ axis are components". Could you explain it in other words?
Thank you!
My native language is not English and can't realize what does the first sentence on the picture sentence mean. In particular, "each angle and the $x$ axis are components". Could you explain it in other words?
Thank you!
They are talking about connected components here. The set $X$ consists of the $x$-axis, along with infinitely many "angles". An angle in this case means one horizontal ray, meeting a line segment from $(0,1)$ at an angle. Here is a hastily-drawn picture of one such "angle":
As you can see from the drawing in your book, $X$ consists of infinitely many such angles, all joined together at $(0,1)$.
If you remove $(0,1)$ from this space, then each of those angles will be connected omponents of the space that is left.