___ \/ 2 ----- = sin(x) 2
___ -\/ 2 ------- = cos(x) 2
(-sqrt(2))/2 = cos(x)
2.35619449019234
x1 = 2.356194490192345
x2 = 8.639379797371932
x3 = -10.21017612416683
x4 = -3.926990816987242