I want to make a plot with a condition in such a way that the function is zero at above some value.  

For example, in the following equation, I need `A[9] = 0` and the plot should go to zero at that value. How I can do it?

    A3[x_] := 
      10/(2.0816*x) (SphericalBesselJ[1, 2.0816*x/
             10]*(-10/(2*2.0816 x) SphericalBesselJ[1, 2.0816*x/10] + 
            1/2 (SphericalBesselJ[0, 2.08*x/10] - 
                 SphericalBesselJ[2, 2.0816*x/10]))*(Sin[Pi/6])^2) +
                 (SphericalBesselJ[1, 2.0816*x/10])^2*(Cos[Pi/6])^2/((2.0816*x)/10)^2;

    Plot[{A3[x]}, {x, -20, 20}, AxesLabel -> {x, z}]