Given the values of $\sin t$ at $t=0^{\circ}, 30^{\circ}, 45^{\circ}, 60^{\circ}$, find the following approximations:
(a) the least squares linear polynomial; (b) the least squares quadratic polynomial; (c) the quadratic Taylor polynomial at $t=0 ;(d)$ the interpolating polynomial; (e) the cubic Taylor polynomial at $t=0 ;(f)$ Graph each approximation and discuss its accuracy.