2. (a) Show that the equation of the tangent at the point P(21, y1) on the circle ity?+2gr+2fy+c = 0 is given by in + yy+ g(3+1)+f(y+ y)+c=0 (b) Find a unit vector parallel to the resultant of vector r1 = 2i + 4j - 5k, r2 = i + 2j + 3k (c) Find the area of the triangle having vertices at P(1, 3, 2),Q(2, -1, 1), R(-1, 2, 3)