1 marker explain !!

[azure talon]

a level maths series and sequences !! happy new years

[open hinge]

n=0: 0
n=1: 1
n=2: 0
n=3: -1

n=4: 0
n=5: 1
n=6: 0
n=7: -1

n=8: 0
....

so period is 4

Or notice that your just turning 90 degrees every time so u start at 0 degrees, then 90 then 180
after 4 90 degree turns ur back where u started