The relationship between these four sectors are:
The plural of radius is what we call radii. For any line that joins the center or is joining the center to any point in the circumference of a circle is what we call radii.
Note:
If there is an infinite line from the center to circumference then is it called infinite radii.
For any line that joins or is joining two points on the circumference of a circle is known as chord and any line touching the circle is what we call as tangent to the circle.
Lastly, the intersection of bisector angles is known as in-center or inscribed.
Below are attached pictures of figures
