acos(3/2 - y)
1 ------------------- ________________ / 2 \/ 1 - (3/2 - y)
-3/2 + y ------------------- 3/2 / 2\ | (3 - 2*y) | |1 - ----------| \ 4 /
2 3*(-3 + 2*y) 1 + ------------------ / 2\ | (3 - 2*y) | 4*|1 - ----------| \ 4 / ---------------------- 3/2 / 2\ | (3 - 2*y) | |1 - ----------| \ 4 /