半圆形

• 丷(two diagonal strokes; division in half)ASSOCIATIVE
• 牛(cow; cattle)ASSOCIATIVE

Using a knife to split a cow in half equally shows the meaning of 半 (half).

• 囗(encircling ring; surrounding loop)RADICAL
• 员(member)PHONETIC

A circle is a shape that is completely enclosed and closed like a member held within embracing arms.

• 开(open; mold; form)ASSOCIATIVE
• 彡(stroke; line)RADICAL

Shape is lines drawn on a frame opening before the eyes.