Lesson 61- Pascal's Triangle

General Triangle:

    The Symmetrical Pattern:
    5C1 = 5C4
  Justification: by symmetry   choosing 1 out is choosing 4 in
 Generalization: nCr = nCn-1


The Recursive Pattern:
5C3 = 4C2 + 4C3
Justification:  add above 2 terms
Generalization: nCr = n-1Cr-1 + n-1Cr