1. Features of an angle: a vertex and two sides (straight).

2. The size of the angle is related to the size of both sides, and has nothing to do with the length of both sides.

3. The angle of painting:

(1) Fixed Vertex.

(2) Draw a straight line from this point.

(3) Draw another side (at right angles, aim at the drawn side with the right angle side and draw a line along the other right angle side).

Classification of angles

1, understanding right angles: the characteristics of right angles.

2. Know acute angle and obtuse angle: acute angle is less than right angle, and obtuse angle is greater than right angle.

3. You can judge the right angle, acute angle and obtuse angle with a triangular ruler: overlap the vertex of the right angle on the triangular ruler with the vertex of the compared angle, then overlap one side of the right angle on the triangular ruler with one side of the compared angle, and finally compare the other side of the right angle on the triangular ruler with the other side of the compared angle. This line is a right angle, the inside is an acute angle and the outside is an obtuse angle.

4. Draw right angles, acute angles and obtuse angles.