Date | November Example questions | Marks available | 2 | Reference code | EXN.1.AHL.TZ0.8 |
Level | Additional Higher Level | Paper | Paper 1 (without calculator) | Time zone | Time zone 0 |
Command term | Find | Question number | 8 | Adapted from | N/A |
Question
The lines l1l1 and l2l2 have the following vector equations where λ, μ∈ℝ and m∈ℝ.
l1 : r1=(3-20)+λ(21m) l2 : r2=(-1-4-2m)+μ(2-5-m)
The plane Π has Cartesian equation x+4y-z=p where p∈ℝ.
Given that l1 and Π have no points in common, find
Show that l1 and l2 are never perpendicular to each other.
the value of m.
the condition on the value of p.
Markscheme
* This sample question was produced by experienced DP mathematics senior examiners to aid teachers in preparing for external assessment in the new MAA course. There may be minor differences in formatting compared to formal exam papers.
attempts to calculate (21m)·(2-5-m) (M1)
=-1-m2 A1
since m2≥0, -1-m2<0 for m∈ℝ R1
so l1 and l2 are never perpendicular to each other AG
[3 marks]
(since l1 is parallel to Π, l1 is perpendicular to the normal of Π and so)
(21m)·(14-1)=0 R1
2+4-m=0
m=6 A1
[2 marks]
since there are no points in common, (3, -2, 0) does not lie in Π
EITHER
substitutes (3, -2, 0) into x+4y-z (≠p) (M1)
OR
(3-20)·(14-1)(≠p) (M1)
THEN
p≠-5 A1
[2 marks]