3.44: Vector section formula; collinear points

0606/13/M/J/25 — Question 10 · 8 marks

3.44 diagram3.44 diagram
(a)
Points AA, BB, CC are collinear with AC=13AB\overrightarrow{AC}=\tfrac{1}{3}\overrightarrow{AB}. Given OA=a\overrightarrow{OA}=\mathbf{a} and OB=b\overrightarrow{OB}=\mathbf{b}, find OC\overrightarrow{OC} in terms of a\mathbf{a} and b\mathbf{b}.
[3]
(b)
Line OAOA is extended to DD with OA:AD=2:7OA:AD=2:7. Point EE on CDCD has OE=mb\overrightarrow{OE}=m\mathbf{b}. Find mm.
[5]