cos(x) = 0
-2*y = 0
0
1.57079632679490
4.71238898038469
x1 = -10.99557428756428 y1 = 0
x2 = 1.570796326794897 y2 = 0
x3 = -1.570796326794897 y3 = 0
x4 = 10.99557428756428 y4 = 0