0 & lt= x & lt=π/2
-2π/3 & lt; =π/3-2x & lt; =π/3
The graph of -cos is inverted,-1
When a<0, 2a < =-2acos <; =-2a,3a+b & lt; = f(x)& lt; =b
3a+b=-5 and b= 1 Look for A, and B looks for A.
When a=0. . . . . . . . . . (Write it yourself, similar to the above)
When a>0 ................................. (write it yourself, similar to the above)