A number with a negative sign "-"in front of a number that is not 0 is called a negative number. ?

It has the opposite meaning to negative number, that is, I learned that numbers other than 0 are called positive numbers (sometimes "+"is added before positive numbers as needed).

Rational number?

Positive integers, 0 and negative integers are collectively called integers, and positive and negative fractions are collectively called fractions. ?

Integers and fractions are collectively called rational numbers. ?

Numbers are usually represented by points on a straight line, which is called the number axis. ?

Three elements of number axis: origin, positive direction and unit length. ?

Take any point on a straight line to represent the number 0, and this point is called the origin.

Numbers with only two different signs are called opposites. (Example: the reciprocal of 2 is-2; The antonym of 0 is 0).

The distance between the point representing the number A on the number axis and the origin is called the absolute value of the number A, and it is recorded as |a|.

The absolute value of a positive number is itself; The absolute value of a negative number is its reciprocal; The absolute value of 0 is 0. Two negative numbers, the larger one has the smaller absolute value. ?

? A preliminary understanding of graphics?

Geometry is also called solid for short. What surrounds the body is the surface. ?

Straight line, ray, line segment?

Axiom of line segment: Of all the connecting lines between two points, the line segment is the shortest (the line segment between two points is the shortest). ?

The length of the line segment connecting two points is called the distance between these two points.

Angle measurement?

1 degree =60 minutes 1 minute =60 seconds 1 fillet =360 degrees 1 flat angle = 180 degrees.

Comparison and calculation of angles?

If the sum of two angles is equal to 90 degrees (right angle), they are called complementary angles, that is, each angle is the complementary angle of the other angle.

If the sum of two angles is equal to 180 degrees (flat angle), it is said that the two angles are complementary, that is, each angle is the complement of the other angle.

The complementary angles of equal angles (same angles) are equal. ?

The complementary angles of equal angles (same angles) are equal.