32   13. Relative to a fixed origin O • the point A has position vector 4i − 3j + 5k • the point B has position vector 4j + 6k • the point C has position vector −16i + pj + 10k where p is a constant. Given that A, B and C lie on a straight line, (a) find the value of p. (3) The line segment OB is extended to a point D so that CD → is parallel to OA → (b) Find | OD →  | , writing your answer as a fully simplified surd. 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