(a) Given two vectors, r1=3i + 2}" 375 and r2=2 +1" + E, show that both vectors lie in the plane 5x 9y z = 0. (Note that the vector equation of a plane in the summary sheets uses r = xi + yj' + 2E). [5 marks] (b) Find an equation of a plane that is perpendicular to the plane, 5x 9y z = 0. and in which the vector r2 = 23 +1" + E lies. [5 marks] (c) Given the position vectors of three points a=i +j + E, b=2i' + 3i + E, c=3 + 2}" + 373, find the equation of the plane passing through all three points. [5 marks]