-1≤cost≤1,
3≥-3cost≥-3,
7≥4-3cost≥1.
max=7.
-3≤3cost≤3,
-5≤3cost-2≤1.
max=1.
-1≤sint≤1,
-3≤3sint≤3,
-1≤3sint+2≤5,
max=5
