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3.14 Vector equation of a lineIB Maths: Analysis and Approaches HL: Subtopic test

10 questions, 27 marks

IB Maths: Analysis and Approaches HL

3.14 Vector equation of a line

Total 27 marks

Name

Class

Date

  1. 1
    The line LL has vector equation r=(1−23)+λ(21−2)\mathbf{r}=\begin{pmatrix}1\\ -2\\ 3\end{pmatrix}+\lambda\begin{pmatrix}2\\ 1\\ -2\end{pmatrix}, λ∈R\lambda\in\mathbb{R}.
    (a)
    Which of the following points lies on LL?
    [1 mark]
    • A(3,−1,5)(3,-1,5)
    • B(2,1,−2)(2,1,-2)
    • C(−1,−1,5)(-1,-1,5)
    • D(5,0,−1)(5,0,-1)
    (b)
    Which of the following is a Cartesian equation of LL?
    [1 mark]
    • Ax−12=y+21=z−3−2\frac{x-1}{2}=\frac{y+2}{1}=\frac{z-3}{-2}
    • Bx+12=y−21=z+3−2\frac{x+1}{2}=\frac{y-2}{1}=\frac{z+3}{-2}
    • Cx−21=y−1−2=z+23\frac{x-2}{1}=\frac{y-1}{-2}=\frac{z+2}{3}
    • Dx−12=y+21=z−32\frac{x-1}{2}=\frac{y+2}{1}=\frac{z-3}{2}
    (c)
    The line MM has equation r=μ(110)\mathbf{r}=\mu\begin{pmatrix}1\\ 1\\ 0\end{pmatrix}. Find the acute angle between LL and MM.
    [2 marks]

    Total for question 1: 4 marks

  2. 2
    In two dimensions, the line ℓ\ell passes through the points P(3,−1)P(3,-1) and Q(7,5)Q(7,5).
    (a)
    Which of the following is a vector equation of ℓ\ell?
    [1 mark]
    • Ar=(3−1)+λ(75)\mathbf{r}=\begin{pmatrix}3\\ -1\end{pmatrix}+\lambda\begin{pmatrix}7\\ 5\end{pmatrix}
    • Br=(46)+λ(3−1)\mathbf{r}=\begin{pmatrix}4\\ 6\end{pmatrix}+\lambda\begin{pmatrix}3\\ -1\end{pmatrix}
    • Cr=(3−1)+λ(46)\mathbf{r}=\begin{pmatrix}3\\ -1\end{pmatrix}+\lambda\begin{pmatrix}4\\ 6\end{pmatrix}
    • Dr=(75)+λ(−46)\mathbf{r}=\begin{pmatrix}7\\ 5\end{pmatrix}+\lambda\begin{pmatrix}-4\\ 6\end{pmatrix}
    (b)
    Which of the following is an equation of ℓ\ell in the form y=mx+cy=mx+c?
    [1 mark]
    • Ay=23x−3y=\frac23x-3
    • By=32x−112y=\frac32x-\frac{11}{2}
    • Cy=32x+72y=\frac32x+\frac72
    • Dy=−32x+72y=-\frac32x+\frac72
    (c)
    Find the coordinates of the point where ℓ\ell crosses the xx-axis.
    [2 marks]

    Total for question 2: 4 marks

  3. 3
    A ship moves with constant velocity. Its position tt hours after noon is given by r=(25)+t(3−4)\mathbf{r}=\begin{pmatrix}2\\ 5\end{pmatrix}+t\begin{pmatrix}3\\ -4\end{pmatrix}, where distances are in kilometres, i\mathbf{i} points east and j\mathbf{j} points north. A lighthouse stands at the point H(12,0)H(12,0).
    (a)
    Find the speed of the ship and its position at 14:30.
    [3 marks]
    (b)
    Find the time at which the ship is closest to the lighthouse, and the distance between them at that time.
    [4 marks]

    Total for question 3: 7 marks

  4. 4
    Engineers are planning straight tunnels underground. Coordinates are in metres, with the zz-axis vertically upwards and the xyxy-plane horizontal. The first tunnel starts at the origin A(0,0,0)A(0,0,0) and passes through the point B(6,3,−2)B(6,3,-2). A second tunnel follows the line r=(100−3)+μ(2−12)\mathbf{r}=\begin{pmatrix}10\\ 0\\ -3\end{pmatrix}+\mu\begin{pmatrix}2\\ -1\\ 2\end{pmatrix}.
    (a)
    (i) Write down a vector equation for the line of the first tunnel.
    (ii) Write the equation of this line in parametric form and in Cartesian form.

    (iii) Find the coordinates of the point on the first tunnel that is 5 m below the level of
    AA.
    [6 marks]
    (b)
    A calculator may be used in this part.
    (i) Find the acute angle between the two tunnels.

    (ii) Find the angle at which the first tunnel descends below the horizontal.
    [6 marks]

    Total for question 4: 12 marks

End of questions