Fold a piece of circular paper in half three times and then unfold it to get three angles of 360 degrees, 180 degrees, and 180 degrees.

1. The angles after folding in half are: the first angle is a complete circle, and its degree is 360 degrees. The second angle is formed by two folds and its measure is 180 degrees. This angle is a semicircle. The third angle is also formed by two folds, and its degree is also 180 degrees, which is the same as the second angle. So, after folding a circular piece of paper in half three times and unfolding it, you will get a full 360-degree circle and two 180-degree semi-circles.

2. Origami skills. Apply even pressure when folding to ensure that the creases are neat and clear. Use your fingers or a smooth, hard object, such as a credit card, to help flatten the paper to ensure accurate fold lines. Precise alignment, during the folding process, make sure the edges and corners are aligned to ensure folding accuracy.

The history of origami

1. Ancient China: The origin of origami is uncertain, but there is evidence that it may have originated in ancient China. In China, ancient culture and traditions include a skill called paper folding, which was recorded as early as the 2nd century BC. This technique was originally used to create decorations for religious ceremonies and celebrations.

2. Development in Japan: Origami has been widely developed and promoted in Japan, becoming the birthplace of modern origami. In Japan, this technique was first used for religious ceremonies and ceremonial decorations, and later evolved into a children's game and handicraft activity. In Japan, origami has been carried forward and has become a popular traditional culture.

3. Spread to the West: Origami art spread to the West in the 19th century, initially as a fashionable hobby and handicraft activity. Westerners began to learn and practice origami, creating their own origami creations while also being influenced by Japanese and Chinese traditions.

4. Modern origami: Origami has been widely developed and used in modern times. It is not only used for children's education and entertainment, but is also regarded as a form of artistic expression. Modern origami works include various complex animals, plants, buildings and abstract shapes. There is even a subject called "origami mathematics", which studies the mathematical principles and applications of origami.