The five corners are 0.5 yuan, that is, half yuan, and the homonym is semicircle.

A semicircle is half of a circle, and its center is the center of a concentric circle. There is only one diameter and countless radii. There is an axis of symmetry.

The semicircle is a special sector-central angle = 180.

A semicircle is a special kind of bow-chord length = diameter.

Area of semicircle =πr? /2

The circumference of a semicircle =(π+2)r