The most common round arch, its line radian is more rounded and smooth, with strong sense of modeling, many applicable styles and no restrictions on spatial position. If a single arch is too monotonous, you can also use the corresponding "round arch" elements, such as multiple doors or mirrors at home, platforms, etc., to push the grid higher.

Taking the circular arch as the midpoint, the lower the arch, the flatter the radian, which is called "flat arch". The lines of the flat arch are soft and attractive, which is very suitable for spaces with low doorways or beams on them.