Answer only one of the following two alternatives. EITHER The lines l₁ and l₂ have equations r = 6i – 3j + s(3i – 4j – 2k) and r = 2i – j – 4k + t(i – 3j – k) respectively. The point P on l₁ and the point Q on l₂ are such that PQ is perpendicular to both l₁ and l₂. Show that the position vector of P is 3i + j + 2k and find the position vector of Q. Find, in the form r = a + λb + µc, an equation of the plane Π which passes through P and is perpendicular to l₁. The plane Π meets the plane r = pi + qj in the line l₃. Find a vector equation of l₃.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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