The points A(1,2,3), B(4,−1,2), C(6,2,6) and D(3,5,7) are the vertices of a quadrilateral ABCD.
Answer the following questions.
(i) Show that ABCD is a parallelogram.
(ii) Obtain the vectors representing the diagonals AC and BD.
(iii) Find, correct to the nearest degree, the angle between the diagonals AC and BD.