If there are 60 books in the college library. in how many ways will these books be arranged on the shelves if 3 of the books are taken at a time with order of arrangement of the books considered

205,320

Step-by-step explanation:

If order matters this is a permutation problem (as opposed to a combination problem).  The permutation of this situation is

₆₀P₃ = and is solved:

The 57 factorials cancel out, leaving us with 60*59*58 which comes to 205,320 different ways to pick 3 books if order matters.

i belive those are the ones that are under 90 degreese.