Question: Connecting Two Lines Piecewise (ASAP)

This is for the infamous Calc 2 Goblet Maple Project

I have tried everything changed all the numbers and got nowhere or worse results. The only thing that accurately works is the example project:

(0, 1.5) and end at (0.5, 0.2). which equals f1(x)=-2.6x+1.5

and f2:=x->0.2+0.05*sin(2*(x-0.5)) which is really 0.2+0.05sin(2x-1)

The goal is to change the example project so it becomes something of my own creation. 

When I change f2:=x->0.4+0.05*sin(2*x-0.5)) it is at least attached but forms a sharp dip down first then connects at the point when it should be smooth curve. It seems you can do anything to the other curve

f3:=x->a*x^3+b*x^2+c*x+d;
x -> a x^3 + b x^2 + c x + d

connection1:=f3(5.5)=f2(5.5);
166.375 a + 30.25 b + 5.5 c + d = 0.3727989445

arc1:=f3(7)=1;
343 a + 49 b + 7 c + d = 1

arc2:=f3(7.5)=0.9;
421.875 a + 56.25 b + 7.5 c + d = 0.9

arc3:=f3(9)=1.6;
729 a + 81 b + 9 c + d = 1.6

values:=solve({eq1,eq2,eq3,eq4},{a,b,c,d});

F:=x->piecewise(x<0.5,f1(x),x>=0.5 and x<5.5,f2(x),x>=5.5,f3(x));

plot(F(x),x=0..9,y=0..4,scaling=constrained);

So how can this be fixed?