【Example 5】Let the diagonals of a convex $n(n \geqslant 4)$-sided polygon have no 3 intersecting at the same point. How many intersection points do these diagonals have?
Solve: The number of intersection points of these diagonals is $C_{n}^{4}$.

The number of intersection points of these diagonals is $C_{n}^{4}$.