Evaluate exact circular-function values by symmetry and periodicity
The angle is measured from the positive horizontal axis in the usual anticlockwise direction
The angle is \(0\ \mathrm{rad}\)
The requested function is \(\cos\)
The angle is measured from the positive horizontal axis in the usual anticlockwise direction
The angle is \(0\ \mathrm{rad}\)
The requested function is \(\cos\)