OABC OABC\,OABC is a parallelogram, with OA⃗=a\vec{OA} = \mathbf{a}OA=a and OC⃗=c\vec{OC} = \mathbf{c}OC=c.
M M\,M is the midpoint of the diagonal OBOBOB.
Find AC⃗\vec{AC}AC in terms of a\mathbf{a}a and c\mathbf{c}c.
Find OM⃗\vec{OM}OM in terms of a\mathbf{a}a and c\mathbf{c}c, simplifying your answer.
Hence prove that the diagonals of a parallelogram bisect one another.
197 exam-style questions on OCR A Level Maths 1.10 Vectors, covering 1.10.1 Vectors in two dimensions, 1.10.2 Vectors in three dimensions (A-level only), 1.10.3 Magnitude and direction of vectors, 1.10.4 Basic operations on vectors, 1.10.5 Position vectors, 1.10.6 Distance between points, 1.10.7 Problem solving using vectors, 1.10.8 Vectors in kinematics, and 1.10 Vectors. Each one has a worked solution and a mark scheme showing where the marks go.