Sin48 cos12+cos48 sin12 =
Sin48cos12 + cos48sin12 = sin(4pi/15)*cos(pi/15)+sin(pi/15)*cos(4pi/15)=sin(α + β) = sinα cosβ + cosα sinβ = sin(4pi/15+pi/15)=sin(5pi/15)=sin(pi/3)=
you best !