Observe the difference and look for the right vertex angle, When there are two lines intersecting at a point, there are () pairs of vertex angles. When there are three lines, there are () pairs of vertex angles. When there are four lines, there are () pairs of vertex angles. When there are n lines, there are () pairs of vertex angles

When there are two lines intersecting at a point, there are (2) pairs of vertex angles. When there are three lines, there are (6) pairs of vertex angles. When there are four lines, there are (12) pairs of vertex angles. When there are n lines, there are n (n-1) pairs of vertex angles

RELATED INFORMATIONS

1. What is opposite vertex angle
2. Observe the following figures to find the opposite vertex angle (excluding horizontal angle) (1) As shown in figure a, there are & nbsp; & nbsp; pairs of vertex angles in the figure; (2) As shown in Figure B, there are & nbsp; & nbsp; pairs of vertex angles in the figure; (3) As shown in Figure C, there are & nbsp; & nbsp; pairs of vertex angles in the figure; (4) This paper studies the relationship between the number of straight lines and the logarithm of opposite vertex angle in (1) ～ (3). If n straight lines intersect at a point, how many pairs of opposite vertex angle can be formed? (5) If there are 2008 lines intersecting at a point, how many pairs of vertex angles can be formed?
3. If two angles are equal, then they are opposite vertex angles
4. Two equal angles are opposite vertex angles. Is that right also: The sum of adjacent complementary angles is 180 degrees, The remaining angles of the two angles are equal, Two complementary angles are also called adjacent complementary angles, also What is the angle formed by the bisector of two adjacent complementary angles?
5. Unequal angles are not opposite to vertex angles Is this proposition true? Give reasons
6. A ^ 2-1 of A-2 divided by (a-1-a + 1 of 2a-1), where a is the root of the equation x ^ 2-x = root 3
7. Given the function f (x) = | x2-2 |, if f (a) ≥ f (b), and 0 ≤ a ≤ B, then the area bounded by the points (a, b) satisfying the condition is___ ．
8. The sum of 987 minus 287 plus 135. Simple calculation method
9. Triple integral calculation: calculate ∫ ∫ ∫ Ω √ X & # 178; + Y & # 178; + Z & # 178; * DV, where Ω: X & # 178; + Y & # 178; + Z & # 178; ≤ X
10. Factorization (2x - y) - 4x + 2Y + 1
11. The property theorem of vertex angle is
12. The properties of vertex angle are as follows______ ．
13. What is the basis for the nature of vertex angle
14. Definition and properties of vertex angle
15. What is the meaning of vertex angle
16. Definition of vertex angle
17. Are the opposite vertex angles equal or are the two opposite vertex angles equal
18. If the two angles are opposite vertex angles, then_________________
19. If two angles are opposite vertex angles and complementary, then the degrees of the two angles are______ ．
20. Two complementary angles cannot be opposite vertex angles