Know the angle, right angle, acute angle and obtuse angle, and know the names of all parts of the angle. Can draw angles, and can judge right angles, acute angles and obtuse angles with a triangular ruler.

The concepts of angle, right angle, acute angle and obtuse angle first appeared, which were limited by the knowledge level and ability of junior two students. Here, students are only required to know what an angle is, what a right angle, an acute angle and an obtuse angle are. An angle has a vertex and two sides and can draw an angle. A triangular ruler can judge the right angle, acute angle and obtuse angle and know the size of the angle.

Related concepts of angle

Complementary angle and complementary angle: if the sum of two angles is 90, it is complementary angle, and if the sum of two angles is180, it is complementary angle. The complementary angles of equal angles are equal, and the complementary angles of equal angles are equal.

Inverse vertex angle: When two straight lines intersect, there is only one common vertex, and both sides of the two corners are opposite extension lines. These two angles are called antipodal angles. Two straight lines intersect to form two pairs of vertex angles. The two opposite angles are equal.

Adjacent complementary angles: two angles have a common edge, and their other edge is an opposite extension line. Two angles with this relationship are adjacent complementary angles.

Internal angle: Two straight lines are cut by a third straight line. If both angles are on the inside of two straight lines and on both sides of the third straight line, then such a pair of angles is called an inner angle.

Inner angle on the same side: two angles are on the same side of the dividing line, and between the two dividing lines, a diagonal with this positional relationship is the inner angle on the same side.

Isomorphism angle: two angles are on the same side of the section line and the same side of two straight lines respectively. Diagonal lines with this positional relationship are called isomorphic angles.

External dislocation angle: two straight lines are cut by a third straight line to form eight angles. If both angles are outside and on both sides of the secant, then such a pair of angles is called the external dislocation angle.

Exterior angle on the same side: two angles are on the same side of the dividing line, and outside the two dividing lines, a pair of angles with this positional relationship are exterior angles on the same side.

Angle with the same terminal edge: An angle with the same starting edge and terminal edge is called an angle with the same terminal edge.