Junior high school will not talk about π radian system in depth, but only a general understanding at most.

What students need to master in junior high school is

The degree of fillet is half that of central angle.

The radian refers to the degree of the central angle.

In addition, the degree of the arc surrounded by the chord tangent angle is the degree of the circumferential angle subtended by the arc.

These three are more important, and a lot of knowledge will gradually extend.