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IGCSE Math B8.F Vector magnitudeTopic Practice

8.F Vector magnitude

Modulus (magnitude) of a vector

Question 25

[Maximum number: 5]
Question image

ABC is a triangle.
AB=(32),BC=(x5x),x>0,AC=5.\overrightarrow{AB}=\begin{pmatrix}3\\-2\end{pmatrix}, \qquad \overrightarrow{BC}=\begin{pmatrix}x\\5x\end{pmatrix}, \qquad x>0, \qquad |\overrightarrow{AC}|=5.
Find AC\overrightarrow{AC} as a column vector.
Show clear algebraic working.

Question 11

[Maximum number: 3]

OX=(42)\overrightarrow{O X}=\binom{-4}{2} and YX=(76)\overrightarrow{Y X}=\binom{-7}{6}

Calculate the modulus of OY\overrightarrow{O Y}

Question 16

The position vector of A is (38)\binom{-3}{8}.
The point B has coordinates (2,-4).
Find AB|\overrightarrow{AB}|.

Question 18

The vectors
p=(x2x1),q=(95)\mathbf p=\begin{pmatrix}x\\2x-1\end{pmatrix}, \qquad \mathbf q=\begin{pmatrix}-9\\5\end{pmatrix}
are such that p=q|\mathbf p|=|\mathbf q|.
Given that x<0, find the value of x.

Question 20

Given that
a=(x22x)\mathbf a=\binom{x-2}{\sqrt{2x}}
where a=5|\mathbf a|=\sqrt5, find the exact value of x.

Question 21(c)

[Maximum number: 2]

The coordinates of point A are (1,8) and the coordinates of point B are (10,-4).

Question image

Calculate the modulus of A P.

Question 21(b)

[Maximum number: 2]

21OX=(25)21 \overrightarrow{O X}=\binom{2}{5} and OY=(27)\overrightarrow{O Y}=\binom{-2}{7}

Calculate XY|\overrightarrow{X Y}|, giving your answer as a surd.

XY=|\overrightarrow{X Y}|=

Question 9

[Maximum number: 5]

The vectors
p=(2x1y),q=(y+3y)\mathbf p=\begin{pmatrix}2x-1\\y\end{pmatrix}, \qquad \mathbf q=\begin{pmatrix}y+3\\-y\end{pmatrix}
are such that p=98|\mathbf p|=\sqrt{98} and
p+q=(70).\mathbf p+\mathbf q=\begin{pmatrix}7\\0\end{pmatrix}.

Question 9(a)

(a)

Show that
x23x9=0.x^2-3x-9=0.
Given that x>0,

[ 5 ]

Question 9(c)

(b)

Find the exact value of q2|\mathbf q|^2.
Show your working clearly.

Question 10(e)

[Maximum number: 3]
Figure 4

Figure 4

Figure 4 shows a trapezium OACB in which OAC=AOB=90\angle O A C=\angle A O B=90^{\circ} so that OB and AC are parallel.
Given that OA=a,OB=b\overrightarrow{O A}=\mathbf{a}, \overrightarrow{O B}=\mathbf{b} and AC=2b\overrightarrow{A C}=2 \mathbf{b},

Given that a=6|\mathbf{a}|=6 cm and b=8|\mathbf{b}|=8 cm,

calculate the length, in cm to 3 significant figures, of OP.

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