Mosaic, to achieve "neither weight nor leakage", therefore, the mosaic of polygons should be 360 degrees.

Any triangle or quadrilateral can be inlaid. Around a point: the internal angle of the triangle and 180 degrees, each angle is used twice, which can make up 360 degrees to complete the mosaic; Quadrilateral internal angles and 360 degrees, each angle is used once, which can make up 360 degrees to complete the splicing.

Regular triangles, regular quadrangles and regular hexagons can all be inlaid.

For the combination of several figures, only the inner angle can be used to make up 360 degrees-if it is made up, it can be inlaid, otherwise it can't.