Type 1: Angle model (three lines are perpendicular to each other).
Type 2: Vertical model (line perpendicular to plane).
Type 3: melon cutting model (two planes are perpendicular to each other).
Type 4: Hamburg model (right-angle prism receives the ball).
The fifth type: folding model.
Type 6: equilateral model.
Type 7: A model in which two right triangles are put together.
Type 8: the problem of catching the ball in the vertebral body.