Question

@Kainui

Answer 1

cos 73pi/4

Answer 2

Well since cos(x+2pi)=cos(x) just find out how many 2pi you have as a remainder and remove them.

Answer 3

A quick hint, since 80 is obviously evenly divisible by 4, then so is 72 since it's just 80-(2*4).

Answer 4

@surjithayer For shame, he needs to work for his answers; this is just giving it to him. You will never be a good tutor if you're too anxious to show off, give away the answer and don't allow them to find the answer for themselves.