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Date	November Example questions	Marks available	3	Reference code	EXN.1.AHL.TZ0.8
Level	Additional Higher Level	Paper	Paper 1 (without calculator)	Time zone	Time zone 0
Command term	Show that	Question number	8	Adapted from	N/A

Question

The lines $l_{1}$ and $l_{2}$ have the following vector equations where $λ, μ \in ℝ$ and $m \in ℝ$ .

$l_{1} : r_{1} = (\begin{matrix} 3 \\ - 2 \\ 0 \end{matrix}) + λ (\begin{matrix} 2 \\ 1 \\ m \end{matrix}) l_{2} : r_{2} = (\begin{matrix} - 1 \\ - 4 \\ - 2 m \end{matrix}) + μ (\begin{matrix} 2 \\ - 5 \\ - m \end{matrix})$

The plane $Π$ has Cartesian equation $x + 4 y - z = p$ where $p \in ℝ$ .

Given that $l_{1}$ and $Π$ have no points in common, find

Show that $l_{1}$ and $l_{2}$ are never perpendicular to each other.

[3]

a.

the value of $m$ .

[2]

b.i.

the condition on the value of $p$ .

[2]

b.ii.

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 $(\begin{matrix} 2 \\ 1 \\ m \end{matrix}) \cdot (\begin{matrix} 2 \\ - 5 \\ - m \end{matrix})$ (M1)

$= - 1 - m^{2}$ A1

since $m^{2} \geq 0, - 1 - m^{2} < 0$ for $m \in ℝ$ R1

so $l_{1}$ and $l_{2}$ are never perpendicular to each other AG

[3 marks]

a.

(since $l_{1}$ is parallel to $Π$ , $l_{1}$ is perpendicular to the normal of $Π$ and so)

$(\begin{matrix} 2 \\ 1 \\ m \end{matrix}) \cdot (\begin{matrix} 1 \\ 4 \\ - 1 \end{matrix}) = 0$ R1

$2 + 4 - m = 0$

$m = 6$ A1

[2 marks]

b.i.

since there are no points in common, $(3, - 2, 0)$ does not lie in $Π$

EITHER

substitutes $(3, - 2, 0)$ into $x + 4 y - z (\neq p)$ (M1)

OR

$(\begin{matrix} 3 \\ - 2 \\ 0 \end{matrix}) \cdot (\begin{matrix} 1 \\ 4 \\ - 1 \end{matrix}) (\neq p)$ (M1)

THEN

$p \neq - 5$ A1

[2 marks]

b.ii.

Examiners report

[N/A]

a.

[N/A]

b.i.

[N/A]

b.ii.

Syllabus sections

Topic 3— Geometry and trigonometry » AHL 3.13—Scalar (dot) product

Show 77 related questions

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Find the acute angle between the two airplanes’ lines of flight. Give your answer in degrees.
18M.1.SL.TZ1.S_9d:
Point D is also on L and has coordinates (8, 4, −9).

Find the area of triangle OCD.
17M.1.SL.TZ1.S_8d.ii:
Hence or otherwise, find one point on ${L_2}$ which is $\sqrt 5$ units from C.
19N.1.SL.TZ0.S_9a.i:
$\overrightarrow {{\text{OA}}} \bullet \overrightarrow {{\text{OC}}}$ .
18M.1.SL.TZ1.S_6:
Six equilateral triangles, each with side length 3 cm, are arranged to form a hexagon.
This is shown in the following diagram.

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17M.2.AHL.TZ2.H_9f:
Find a vector perpendicular to the plane Π $_3$ .
17M.2.AHL.TZ2.H_9a:
Find the vector equation of the line (BC).
17M.1.AHL.TZ1.H_5a:
Find the area of the parallelogram ABCD.
18N.1.SL.TZ0.S_5:
Consider the vectors a = $\left( {\begin{array}{*{20}{c}} 3 \\ {2p} \end{array}} \right)$ and b = $\left( {\begin{array}{*{20}{c}} {p + 1} \\ 8 \end{array}} \right)$ .

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17M.1.SL.TZ1.S_8d.i:
Find a unit vector in the direction of ${L_2}$ .
17M.2.AHL.TZ2.H_9d:
Show that the line (BC) lies in the plane Π $_1$ .
16N.1.SL.TZ0.S_4a:
Find a vector equation of the line that passes through P and Q.
18N.2.SL.TZ0.S_8d:
Find the area of triangle ABC.
17N.1.SL.TZ0.S_9a.i:
Show that $\overrightarrow {{\text{AB}}} = \left( {\begin{array}{*{20}{c}} 2 \\ { - 1} \\ 1 \end{array}} \right)$ .
18M.2.SL.TZ2.S_8c:
Find the area of triangle PQR.
16N.1.SL.TZ0.S_4b:
The line through P and Q is perpendicular to the vector 2i $+$ nk. Find the value of $n$ .
18N.1.AHL.TZ0.H_5a:
Find and simplify an expression for a • b in terms of $t$ .
17N.1.SL.TZ0.S_9b:
Find the value of $p$ .
18M.1.SL.TZ2.S_1a:
Find a vector equation for L₁.
19N.1.SL.TZ0.S_9a.ii:
$\overrightarrow {{\text{OB}}} \bullet \overrightarrow {{\text{OC}}}$ .
22M.2.AHL.TZ1.7c:
Find $q$ such that $| q | = | b |$ and $q$ is perpendicular to $a$ .
18N.2.SL.TZ0.S_8b.ii:
Show that $\overrightarrow {{\text{AC}}} = \left( {\begin{array}{*{20}{c}} 8 \\ { - 10} \\ { - 1} \end{array}} \right)$ .
22M.2.AHL.TZ2.11e:
Let $D (t)$ represent the distance between airplane $A$ and airplane $B$ for $0 \leq t \leq 2.5$ .

Find the minimum value of $D (t)$ .
18M.1.SL.TZ1.S_9b.i:
Find a vector equation for L.
17M.1.SL.TZ1.S_8a.ii:
Hence, write down a vector equation for ${L_1}$ .
EXN.2.AHL.TZ0.11d.ii:
Hence determine the minimum distance, $d_{min}$ , from $D$ to $Π$ .
19M.2.SL.TZ2.S_7:
The vector equation of line $L$ is given by r $= \left( {\begin{array}{*{20}{c}} { - 1} \\ 3 \\ 8 \end{array}} \right) + t\left( {\begin{array}{*{20}{c}} 4 \\ 5 \\ { - 1} \end{array}} \right)$ .

Point P is the point on $L$ that is closest to the origin. Find the coordinates of P.
19M.1.SL.TZ2.S_2b:
perpendicular.
18N.2.SL.TZ0.S_8a.i:
Find $\overrightarrow {{\text{AB}}}$ .
17M.2.AHL.TZ2.H_9c:
Find the Cartesian equation of the plane Π $_1$ , which passes through C and is perpendicular to $\overrightarrow {{\rm{OA}}}$ .
18N.2.SL.TZ0.S_8a.ii:
Find $\left| {\overrightarrow {{\text{AB}}} } \right|$ .
18N.2.SL.TZ0.S_8c:
Find the angle between $\overrightarrow {{\text{AB}}}$ and $\overrightarrow {{\text{AC}}}$ .
18M.1.AHL.TZ2.H_1:
The acute angle between the vectors 3i − 4j − 5k and 5i − 4j + 3k is denoted by θ.

Find cos θ.
17M.2.AHL.TZ2.H_9b:
Determine whether or not the lines (OA) and (BC) intersect.
19N.1.SL.TZ0.S_9b:
Given that ${\text{A}}\widehat {\text{O}}{\text{C}} = {\text{B}}\widehat {\text{O}}{\text{C}}$ , show that $k = 7$ .
18M.2.SL.TZ2.S_8a.ii:
Find $\left| {\mathop {{\text{PQ}}}\limits^ \to } \right|$ .
EXN.2.AHL.TZ0.11a:
Find the vectors $\vec{AB}$ and $\vec{AC}$ .
17N.1.SL.TZ0.S_9a.ii:
Find a vector equation for $L$ .
21M.1.AHL.TZ2.5:
Given any two non-zero vectors, $a$ and $b$ , show that ${|a \times b|}^{2} = {|a|}^{2} {|b|}^{2} - {(a \cdot b)}^{2}$ .
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17N.2.SL.TZ0.S_3a:
Find $\left| {\overrightarrow {{\text{AB}}} } \right|$ .
EXN.2.AHL.TZ0.11b:
Use a vector method to show that $B \hat{A} C = 60 °$ .
17M.1.SL.TZ1.S_8a.i:
Find $\overrightarrow {AB}$ .
19M.1.AHL.TZ1.H_1:
Let a = $\left( {\begin{array}{*{20}{c}} 2 \\ k \\ { - 1} \end{array}} \right)$ and b = $\left( {\begin{array}{*{20}{c}} { - 3} \\ {k + 2} \\ k \end{array}} \right)$ , $k \in \mathbb{R}$ .

Given that a and b are perpendicular, find the possible values of $k$ .
18M.1.SL.TZ1.S_9a:
Show that $\mathop {{\text{AB}}}\limits^ \to = \left( \begin{gathered} \,6 \hfill \\ \,8 \hfill \\ - 5 \hfill \\ \end{gathered} \right)$
18N.2.SL.TZ0.S_8b.i:
Find the value of $y$ .
18M.2.SL.TZ2.S_8a.i:
Find $\mathop {{\text{PQ}}}\limits^ \to$ .
17N.1.SL.TZ0.S_9c:
The point D has coordinates $({q^2},{\text{ }}0,{\text{ }}q)$ . Given that $\overrightarrow {{\text{DC}}}$ is perpendicular to $L$ , find the possible values of $q$ .
21N.2.AHL.TZ0.11a.i:
Find the vector $\vec{AB}$ and the vector $\vec{AC}$ .
21N.2.AHL.TZ0.11a.ii:
Hence find the equation of $Π_{1}$ , expressing your answer in the form $a x + b y + c z = d$ , where $a, b, c, d \in ℤ$ .
21N.2.AHL.TZ0.11d.i:
Find the reflection of the point $B$ in the plane $Π_{3}$ .
21N.2.AHL.TZ0.11d.ii:
Hence find the vector equation of the line formed when $L$ is reflected in the plane $Π_{3}$ .
21N.2.AHL.TZ0.11c.i:
Show that at the point $P, λ = \frac{3}{4}$ .
21N.2.AHL.TZ0.11c.ii:
Hence find the coordinates of $P$ .
18M.2.SL.TZ2.S_8d:
Hence or otherwise find the shortest distance from R to the line through P and Q.
17M.1.SL.TZ2.S_2b:
Given that c = a + 2b, find c.
17M.1.SL.TZ2.S_2a:
Find the value of $k$ .
19M.1.SL.TZ1.S_6:
The magnitudes of two vectors, u and v, are 4 and $\sqrt 3$ respectively. The angle between u and v is $\frac{\pi }{6}$ .

Let w = u − v. Find the magnitude of w.
18M.1.SL.TZ1.S_9c.ii:
Write down the value of angle OBA.
17M.2.AHL.TZ2.H_9g:
Find the acute angle between the planes Π $_2$ and Π $_3$ .
18M.1.SL.TZ1.S_9b.ii:
Point C (k , 12 , −k) is on L. Show that k = 14.
17N.2.SL.TZ0.S_3b:
Let $\overrightarrow {{\text{AC}}} = \left( {\begin{array}{*{20}{c}} 3 \\ 0 \\ 0 \end{array}} \right)$ . Find ${\rm{B\hat AC}}$ .
18M.1.SL.TZ2.S_1b:
The vector $\left( \begin{gathered} 2 \hfill \\ p \hfill \\ 0 \hfill \\ \end{gathered} \right)$ is perpendicular to $\mathop {{\text{AB}}}\limits^ \to$ . Find the value of p.
EXN.2.AHL.TZ0.11c:
Show that the Cartesian equation of the plane $Π$ that contains the triangle $ABC$ is $- x + y + z = - 2$ .
EXN.2.AHL.TZ0.11d.i:
Find a vector equation of the line $L$ .
18N.1.AHL.TZ0.H_5b:
Hence or otherwise, find the values of $t$ for which the angle between a and b is obtuse .
17M.2.AHL.TZ2.H_9e:
Verify that 2j + k is perpendicular to the plane Π $_2$ .
19M.1.SL.TZ2.S_2a:
parallel.
19N.1.SL.TZ0.S_9c:
Calculate the area of triangle ${\text{AOC}}$ .
17M.1.SL.TZ1.S_8c:
The lines ${L_1}$ and ${L_1}$ intersect at $C(9,{\text{ }}13,{\text{ }}z)$ . Find $z$ .
18M.1.SL.TZ1.S_9c.i:
Find $\mathop {{\text{OB}}}\limits^ \to \, \bullet \mathop {{\text{AB}}}\limits^ \to$ .
17M.1.AHL.TZ1.H_5b:
By using a suitable scalar product of two vectors, determine whether ${\rm{A\hat BC}}$ is acute or obtuse.
17M.1.SL.TZ1.S_8b:
A second line ${L_2}$ , has equation r = $\left( {\begin{array}{*{20}{c}} 1 \\ {13} \\ { - 14} \end{array}} \right) + s\left( {\begin{array}{*{20}{c}} p \\ 0 \\ 1 \end{array}} \right)$ .

Given that ${L_1}$ and ${L_2}$ are perpendicular, show that $p = 2$ .
EXN.2.AHL.TZ0.11e:
Find the volume of right-pyramid $ABCD$ .
21M.1.AHL.TZ2.8a:
Show that $l_{1}$ and $l_{2}$ do not intersect.
21M.1.AHL.TZ2.8b:
Find the minimum distance between $l_{1}$ and $l_{2}$ .
21N.2.AHL.TZ0.11b:
The line $L$ is the intersection of $Π_{1}$ and $Π_{2}$ . Verify that the vector equation of $L$ can be written as $r = (\begin{matrix} 0 \\ - 2 \\ 0 \end{matrix}) + λ (\begin{matrix} 1 \\ 1 \\ - 1 \end{matrix})$ .

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Topic 3— Geometry and trigonometry » AHL 3.14—Vector equation of line

Topic 3— Geometry and trigonometry