O/n 2006
25
ok for this question between X and Y u will find one full wave that would be 2pie
from X to the beginning of that full wave the distance is 90 degree or pie/2 same thing
and from Y to the end of that full wave the distance is also 90 degrees or pie/2
add all of these together
90 degrees + 90 degrees= pie
pie + 2pie (the middle wave we found out) = 3 pie
therefore C