Help with interpreting math symbol in statement

[BobS0327]

The panel width and height equals twice the radius R, and all the angles α total 360

The above is a statement from a graphics programming book that I am reading. Unfortunately, my understanding of math symbols is nill. I would greatly appreciate the interpretation of the α symbol in the above statement from the book. The chapter is describing a circle which is broken up into equal sized "pie slices".

 

[wjm11]

Help with interpreting math symbol in statement

The panel width and height equals twice the radius R, and all the angles α total 360


The above is a statement from a graphics programming book that I am reading. Unfortunately, my understanding of math symbols is nill. I would greatly appreciate the interpretation of the α symbol in the above statement from the book. The chapter is describing a circle which is broken up into equal sized "pie slices".

All circles comprise 360 degrees. If we cut a circle into pie slices, all the central angles (at the pie slice points) must add up to 360 degrees. If all the slices are the same size, then all the central angles are the same number of degrees. For example, if we cut the circle into 6 equal slices, all the central angles (a) will each equal 60 degrees. This is probably the "a" you are referring to, though I can't be sure as you have not provided any picture.

 

[BobS0327]

I've attached a JPG image of an excerpt of the book. Unfortunately, I'm math challenged and do not have a complete understanding of what the author is trying to explain.

 

[BobS0327]

Where does this come from (part of your 1st post):
"The panel width and height equals twice the radius R" ?

That seems to be saying that the perimeter of the "rectangle"
is equal to the diameter of the circle......or that R = H + W.

That sure doesn't appear to be the case according to diagram
...unless diagram is not to scale; anyway, R = H + W is not
a requirement to solve...

What is it exactly that's given? H and W and nothing else?

Below is an excerpt from the book where I found the above quote..

The panel width and height equals twice the radius R, and all the angles α total 360 degrees.
For a particular child element size, the larger the radius, the smaller the angle. There are two
general ways to go about apportioning space for the children: If the size of the panel is fixed,
angles can be apportioned based on the size of each element. This approach is best if you
expect the children to vary widely in size.

The H and W are the Height and Width of the child element which is the rectangle in the pie.

I've attached a second JPG image to provide more information.

With all your explanations, this is starting to make sense to me.