Choose all answers that apply

I think it's going to be 1,3,4

For sine, the angles with whole values would be 90 degrees and 270 degrees, having a value of 1 and -1 respectively. Similarly for the cosine function, the only angles with a whole number value would be 0 degrees and 180 degrees, with the values of 1 and -1 respectively.

From that, cos 0 degrees = 1.