picture below, a through d please.

4. Consider the piecewise defined function sin(x2y) f (x, y ) = x2 ty2 if ( x, y) # (0, 0) 0 if ( x, y) = (0, 0) (a) (2 pts) Compute or of (0, 0) and 24 (0, 0). (b) (2 pts) Determine an equation of the "only candidate" to be the tangent plane at (0, 0, f (0, 0)). (c) (4 pts) Consider the curve with parametric equation r(t) = (t, t, f (t, t)). Determine the unit tangent vector T(0). (d) (2 pts) Is the function f(x, y) differentiable at (0, 0)? Explain