1, the figure composed of two rays drawn from a point is called an angle. An angle consists of a vertex and two sides.

2. Fillet: The two sides of the corner overlap like rays, and the fillet is equal to 360, which is equal to two right angles and four right angles.

3. Right angle is less than obtuse angle and greater than acute angle.

The longer the sides of an angle are, the bigger the angle is.

5. If the sum of two acute angles is 90, it is a right angle, such as 30+60 = 90, 45+45 = 90.