Wedge: is this what you call this?
I thought that was called a ‘sector’ or something like that?
yes, you're right! i think wedge is just an easier way of saying it.
@rz923 This shape is called a sector in maths. A sector is a plane figure that is enclosed by two radii of a circle or ellipse and the arc between them, such as the one Prof. Loh draw. A wedge is a tool that tapers to a thin edge. They have different meanings, but Prof. Loh just used the word "wedge" to make it easier to visualize and understand.