y=sine(x)/x . . .
av form d(uv)=udv/dx +v*du/dx
dy/dx=[kosine(x)/x ] -sine(x)/x^2
me thank yu wanna EVALUATE y at x=pi/3=60 deg
or x=1.04719755 radians
y=kosine(60)/1.04719755 -sine(60)/1.04719755^2 . .
=0.5/1.04719755 -0.866025408/1.096622709...
=0.477464829 -0.789720472...
=-0.312255643