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Unit vector making given angles with given vectors

This type of question, asked 2 times: 29 Jan 2024, 4 Apr 2024. All 2 questions below, oldest first.

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  1. Question 1

    29 Jan 2024

    170
    Let a unit vector u^=xi^+yj^+zk^\widehat{u}=x\widehat{i}+y\widehat{j}+z\widehat{k} make angles π2,π3\frac{\pi}{2},\frac{\pi}{3} and 2π3\frac{2\pi}{3} with the vectors 12i^+12k^,12j^+12k^\frac{1}{\sqrt{2}}\widehat{i}+\frac{1}{\sqrt{2}}\widehat{k},\frac{1}{\sqrt{2}}\widehat{j}+\frac{1}{\sqrt{2}}\widehat{k} and 12i^+12j^\frac{1}{\sqrt{2}}\widehat{i}+\frac{1}{\sqrt{2}}\widehat{j} respectively. v→=12i^+12j^+12k^\overrightarrow{v}=\frac{1}{\sqrt{2}}\widehat{i}+\frac{1}{\sqrt{2}}\widehat{j}+\frac{1}{\sqrt{2}}\widehat{k}, then ∣u^−v→∣2|\widehat{u}-\overrightarrow{v}|^{2} is equal to

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  2. Question 2

    4 Apr 2024

    71
    Let a unit vector which makes an angle of 60∘60^{\circ} with 2i^+2j^−k^2\widehat{i}+ 2\widehat{j}-\widehat{k} and an angle of 45∘45^{\circ} with i^−k^\widehat{i}-\widehat{k} be C→\overrightarrow{C}. Then C→+(−12i^+132j^−23k^)\overrightarrow{C}+\left( -\frac{1}{2}\widehat{i}+\frac{1}{3\sqrt{2}}\widehat{j}-\frac{\sqrt{2}}{3}\widehat{k} \right) is:

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