The classification of the first volume of mathematics in the fourth grade of primary school by Wing Education Press; There are six writing angles in the lecture record. Let's explain it again.

Because > 0 < 90 is called acute angle. An angle equal to 90 degrees is called a right angle. The angle > 90 < 180 is an obtuse angle, and the angle equal to 180 is a right angle. The angle of >180 < 360 is called the best angle. An angle equal to 360 is called a fillet. Therefore, wing education publishing house's classification of the corners of the first volume of mathematics in the fourth grade of primary school can be explained from six aspects.

The positive angle is the angle of counterclockwise rotation. In geometry, an angle is a geometric object composed of two rays with a common endpoint.