The lines l₁ and l₂ have equations r = 6i + 2j + 7k + λ(i + j) and r = 4i + 4j + μ(−6j + k) respectively. The point P on l₁ and the point Q on l₂ are such that PQ is perpendicular to both l₁ and l₂. Find the position vectors of P and Q.
- The lines l₁ and l₂ have equations r = 6i + 2j + 7k + λ(i + j) and r = 4i + 4j + μ(−6j + k) respectively. The point P on l₁ and the point Q on l₂ are such that PQ is perpendicular to both l₁ and l₂. Find the position vectors of P and Q.[8]
Mark scheme
Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.
- [2] Finds PQ.
- [1] Uses that dot product of PQ with line directions is 0. Or, alternatively, PQ is multiple of common perpendicular.
- [1] Deduces one equation. CWO.
- [1] Deduces second equation. CWO.
- [2] Solves simultaneous equations.
- [1] States OP and OQ.
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