D1.3. The three vertices of a triangle are located at A(6, -1, 2), B(-2,3,-4). and C(-3, 1, 5). Find: (a) RAB; (b) RAC; (c) the angle BAC at vertex A; (d) the (vector) projection of RAB on RAC D1.4. The three vertices of a triangle are located at A(6, -1, 2), B(-2, 3,-4), and C(-3, 1, 5). Find: (a) RAB X RAC; (b) the area of the triangle; (c) a unit vector perpendicular to the plane in which the triangle is located. D1.5. (a) Give the rectangular coordinates of the point C(p = 4.4, = -115°, z = 2). (b) Give the cylindrical coordinates of the point D(x = -3.1, y = 2.6, z=-3). (c) Specify the distance from C to D. D1.6. Transform to cylindrical coordinates: (a) F = 10a-8a,+6a, at point P(10,-8, 6); (b) G = (2x+y)a, -(y-4x)ay at point Q(p. o, z). D1.7. Given the two points, C(-3, 2, 1) and D(r=5,0=20°, = -70°), find: (a) the spherical coordinates of C; (b) the rectangular coordinates of D; (c) the distance from C to D.