若角A,B满足-π/2若角A,B满足-π/2若角A,B满足-π/2-3π/2<2A-B<π/2你可以取极值,先令A=B,则2A-B=A=B,而-π/2然后令A=-π/2,B=π/2,则2A-B=-3π/2所以-3π/2<2A-B<π/2
若角A,B满足-π/2-3π/2<2A-B<π/2你可以取极值,先令A=B,则2A-B=A=B,而-π/2然后令A=-π/2,B=π/2,则2A-B=-3π/2所以-3π/2<2A-B<π/2