First, notice that for the angle of 0 degrees,we have the following:
as we can see, when the angle is 0 degrees, we have all trivial results.
Next, for the angle of 90 degree,we have the following:
in this case, we get an undefined result.
Therefore, 0 and 90 are not included in the table because of its trivial results (1, 0 and undefined)