The vector equation of the tangent line at point r of curve represented by the intersectng surfaces f, (x, y, z) = 0 and f,(x, y, z) = 0 is (a) -r)x vf, = 0 (c)

The vector equation of the tangent line at point r of curve represented by the intersectng surfaces f, (x, y, z) = 0 and f,(x, y, z) = 0 is (A) -r)x Vf, = 0 (C) r-rx (Vf, x Vf,) = 0 19. (r-r) Vf = 0 Ir-ro Vf,, Vf] = 0 (B) (D) 20. The value af tha ista