Further Mathematics · OCR H245 · Option A · Topic 8.04

Further vectors

Vector product.

  • 1 sub-topic
  • Taught in Year 12
  • 17 practice questions
  • 1 animated lesson

What the specification says

Every sub-topic OCR can examine in this topic, with its reference number from the official specification. The Y12 and Y13 tags show when each sub-topic is usually taught.

  1. 8.04a-eVector productY12

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Easy, medium and hard questions from this topic, each with a worked solutions and the mark for every step. All 17 questions in this topic, free, no account needed.

Further vectors

Easy

Volumes from the scalar triple product · Year 12 · 1 mark

  1. Three edges of a tetrahedron that meet at one vertex are given by the vectors aa, bb and cc. What is its volume?
    (1)

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  1. A tetrahedron has one sixth of the volume of the parallelepiped with the same three edges.CC: 16∣a⋅(b×c)∣\tfrac{1}{6}|\mathbf{a} \cdot (\mathbf{b} \times \mathbf{c})|

Total1

  • MMethod mark: for a correct method, even with a slip.
  • AAccuracy mark: for a correct answer from a correct method.
  • BIndependent mark: for a correct fact or result on its own, with no method needed.
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Further vectors

Medium

Scalar triple product · Year 12 · 2 marks

  1. Find the volume of the parallelepiped with edges −2j-2\mathbf{j}, i\mathbf{i}+2j{}+ 2\mathbf{j}+3k{}+ 3\mathbf{k}, −2i-2\mathbf{i}+2j{}+ 2\mathbf{j}+k{}+ \mathbf{k}.
    (2)

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  1. ∣a⋅(b×c)∣|\mathbf{a}\cdot(\mathbf{b} \times \mathbf{c})|
  2. 1414

Total2

  • MMethod mark: for a correct method, even with a slip.
  • AAccuracy mark: for a correct answer from a correct method.
  • BIndependent mark: for a correct fact or result on its own, with no method needed.
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Further vectors

Hard

Volume of a tetrahedron · Year 12 · 5 marks

The points AA, BB and CC have position vectors (−211)\begin{pmatrix} -2 \\ 1 \\ 1 \end{pmatrix}, (2−21)\begin{pmatrix} 2 \\ -2 \\ 1 \end{pmatrix} and (1−2k)\begin{pmatrix} 1 \\ -2 \\ k \end{pmatrix} relative to the origin OO, where kk is a constant. The tetrahedron OABC has volume 3.
  1. Find the possible values of kk.
    (5)
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  1. The volume of a tetrahedron.VV=16∣a⋅(b×c)∣{}= \tfrac{1}{6}|\mathbf{a}\cdot(\mathbf{b} \times \mathbf{c})|
  2. b×c\mathbf{b} \times \mathbf{c}=(2−2k1−2k−2){}= \begin{pmatrix} 2 - 2 k \\ 1 - 2 k \\ -2 \end{pmatrix}
  3. The scalar triple product, then the modulus.∣2k−5∣=18|2 k - 5| = 18
  4. kk=−132 or 232{}= - \frac{13}{2} \text{ or } \frac{23}{2}

Total5

  • MMethod mark: for a correct method, even with a slip.
  • AAccuracy mark: for a correct answer from a correct method.
  • BIndependent mark: for a correct fact or result on its own, with no method needed.
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