ABCD is a parallelogram (labelled anticlockwise) with AB = p and AD = q. M is the midpoint of AD, N is the midpoint of AB and R is one-quarter of the way along AC from A. Find the following in terms of p and q (in the form_p+_q):
i AM
ii AN
iii AC
iv AR
v MR
vi RN
b Hence show that M, N and R all lie on a straight line (by showing that MR is parallel to RN).
c Find the ratio MR: MN.​