Mathematics 9709 · AS & A Level · Vectors

Vectors — practice question

Relative to origin $O$, the position vectors of points $A$ and $B$ are $\overrightarrow{OA} = 2\mathbf{i} - \mathbf{j}$ and $\overrightarrow{OB} = \mathbf{j} - 2\mathbf{k}$.
(a)[4]

Show that $OA=OB$ and use a scalar product to determine angle $AOB$ in degrees.

(b)[6]

Let $M$ be the midpoint of $AB$. A point $P$ on the line through $O$ and $M$ satisfies $PA : OA = \sqrt{7} : 1$. Find the possible position vectors of $P$.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Show that $OA$ and $OB$ each equal $\sqrt5$.

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