SATHEE: Kinematics Question 129

Kinematics Question 129

Question: If $\vec{A} = 2 \hat{i} + 4 \hat{j} - 5 \hat{k}$ the direction of cosines of the vector $\vec{A}$ are

Options:

A) $\frac{2}{\sqrt{45}}, \frac{4}{\sqrt{45}} a n d \frac{- 5}{\sqrt{45}}$

B) $\frac{1}{\sqrt{45}}, \frac{2}{\sqrt{45}} a n d \frac{3}{\sqrt{45}}$

C) $\frac{4}{\sqrt{45}}, 0 a n d \frac{4}{\sqrt{45}}$

D) $\frac{3}{\sqrt{45}}, \frac{2}{\sqrt{45}} a n d \frac{5}{\sqrt{45}}$

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Answer:

Correct Answer: A

Solution:

$\vec{A} = 2 \hat{i} + 4 \hat{j} - 5 \hat{k}$

$| \vec{A} | = \sqrt{{(2)}^{2} + {(4)}^{2} + {(- 5)}^{2}} = \sqrt{45}$

$\cos α = \frac{2}{\sqrt{45}}, \cos β = \frac{4}{\sqrt{45}}, \cos γ = \frac{- 5}{\sqrt{45}}$

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Kinematics Question 129

Question: If A→=2i^+4j^−5k^ the direction of cosines of the vector A→ are

Options:

Answer:

Solution:

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Question: If $\vec{A} = 2 \hat{i} + 4 \hat{j} - 5 \hat{k}$ the direction of cosines of the vector $\vec{A}$ are