2. Polynomial: The sum of several monomials is called polynomial.

3. Algebraic expressions: monomials and polynomials are collectively referred to as algebraic expressions.

4. The number of monomials: The sum of the indices of all the letters in the monomials is called the number of monomials.

5. Degree of Polynomial: The degree of the term with the highest degree in the polynomial is the degree of the polynomial.

6. Complementary angle: The sum of two angles is 90 degrees, and these two angles are called complementary angles.

7. Complementary angle: The sum of two angles is 180 degrees, and these two angles are called complementary angles.

8. Relative vertex angles: two corners have a common vertex, and two sides of one corner are opposite to the extension lines of two sides of the other corner. These two angles are antipodal angles.

9. Common angle: In the "three-line octagon", the angles at the same position are common angles.

10, internal angle: in the "three-line octagon", the angle sandwiched between two straight lines is the internal angle.

1 1, ipsilateral inner angle: in "trilinear octagon", the angle on the same side of trilinear is ipsilateral inner angle.

12, significant number: an approximation, starting with the first number on the left that is not 0 and ending with the exact 1, all numbers are significant numbers.