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Find a vector from its cross product and dot product with a given vector

This type of question, asked 9 times: 2 May 2023 S2, 3 May 2023 S2, 9 May 2023 S1, 10 May 2023 S2, 9 May 2024 S2, 13 May 2024 S2, 25 Apr 2025 S1, 16 Apr 2026 S1, 18 Apr 2026 S2. All 9 questions below, oldest first.

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  1. Question 1

    2 May 2023 S2

    123
    If C is a non-zero scalar and A, B are non-zero vectors with A⃗⊥B⃗\vec{A}\perp\vec{B}, A⃗⋅X⃗=C\vec{A}\cdot\vec{X}=C and A⃗×X⃗=B⃗\vec{A}\times\vec{X}=\vec{B}, then X⃗\vec{X} is given by

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  2. Question 2

    3 May 2023 S2

    133
    Let a⃗=j^−k^\vec{a}=\hat{j}-\hat{k} and c⃗=i^−j^−k^\vec{c}=\hat{i}-\hat{j}-\hat{k}. Then the vector b⃗\vec{b} satisfying a⃗×b⃗+c⃗=0⃗\vec{a}\times\vec{b}+\vec{c}=\vec{0} and a⃗⋅b⃗=3\vec{a}\cdot\vec{b}=3, is

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  3. Question 3

    9 May 2023 S1

    137
    If a⃗=i^+j^+k^\vec{a}=\hat{i}+\hat{j}+\hat{k}, a⃗⋅b⃗=1\vec{a}\cdot\vec{b}=1 and a⃗×b⃗=j^−k^\vec{a}\times\vec{b}=\hat{j}-\hat{k}, then b⃗\vec{b} is

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  4. Question 4

    10 May 2023 S2

    117
    If a⃗=j^−k^\vec{a} = \hat{j}-\hat{k} and c⃗=i^−j^−k^\vec{c} = \hat{i}-\hat{j}-\hat{k}, then the vector b⃗\vec{b} satisfying a⃗×b⃗+c⃗=0⃗\vec{a}\times\vec{b}+\vec{c}=\vec{0} and a⃗⋅b⃗=3\vec{a}\cdot\vec{b}=3 is

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  5. Question 5

    9 May 2024 S2

    119
    a⃗=i^+j^+k^,  b⃗=j^−k^\vec{a} = \hat{i}+\hat{j}+\hat{k},\;\vec{b} = \hat{j}-\hat{k}, then vector r⃗\vec{r} satisfying a⃗×r⃗=b⃗\vec{a}\times\vec{r} = \vec{b} and a⃗⋅r⃗=3\vec{a}\cdot\vec{r} = 3 is

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  6. Question 6

    13 May 2024 S2

    147
    a⃗=2i^+3j^+4k^,b⃗=i^−2j^+k^,c⃗=i^+j^−k^\vec{a}=2\hat{i}+3\hat{j}+4\hat{k},\vec{b}=\hat{i}-2\hat{j}+\hat{k},\vec{c}=\hat{i}+\hat{j}-\hat{k} are three vectors. For a vector r⃗\vec{r} with r⃗×a⃗=b⃗\vec{r}\times\vec{a}=\vec{b} and r⃗⋅c⃗=3\vec{r}\cdot\vec{c}=3, ∣r⃗∣|\vec{r}| is

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  7. Question 7

    25 Apr 2025 S1

    105
    If a‾=i^+j^+k^,b‾=j^−k^\overline{a}=\widehat{i}+\widehat{j}+\widehat{k},\overline{b}=\widehat{j}-\widehat{k} then a vector c‾\overline{c} such that a‾×c‾=b‾\overline{a}\times\overline{c}=\overline{b} and a‾⋅c‾=3\overline{a}\cdot\overline{c}= 3 is

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  8. Question 8

    16 Apr 2026 S1

    87
    Let aˉ=i^+j^,cˉ=i^−j^\bar{a} = \hat{i} + \hat{j}, \bar{c} = \hat{i} - \hat{j} and a vector bˉ\bar{b} be such that aˉ×bˉ=cˉ\bar{a} \times \bar{b} = \bar{c} and aˉ⋅bˉ=3\bar{a}\cdot\bar{b} = 3 then ∣bˉ∣=|\bar{b}| =

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  9. Question 9

    18 Apr 2026 S2

    93
    If aˉ⋅bˉ=β\bar{a}\cdot\bar{b} = \beta and aˉ×bˉ=cˉ\bar{a} \times \bar{b} = \bar{c} then aˉ=\bar{a} =

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