Physics, asked by poojankalgi, 10 months ago

10. Given: A = 3i - 4j –2k and B = 2î + 4 j - 5k .
The angle which A + B makes with Y-axis is
(a) 0°
(b) 45°
(c) 60°
(d) 90°​

Answers

Answered by Anonymous
21

Answer:

\displaystyle{\theta=90}

d . option is correct .

Explanation:

Given :

\displaystyle{\vec A=3\hat{i}-4\hat{j}-2\hat{k} \ and}\\\\\\\displaystyle{\vec B=2\hat{i}+4\hat{j}-5\hat{k}}\\\\\\\displaystyle{Now }\\\\\\{\displaystyle \vec A+\vec B\implies 3\hat{i}-4\hat{j}-2\hat{k}+2\hat{i}+4\hat{j}-5\hat{k}}\\\\\\\displaystyle{\vec A+\vec B\implies\hat{i}-7\hat{k}}

Here coefficient of j = 0

Now angle with y - axis

\displaystyle{\cos\theta=\dfrac{y}{\sqrt{x^2+y^2+z^2}}}\\\\\\\displaystyle{\cos\theta=\dfrac{0}{\sqrt{x^2+y^2+z^2}}}\\\\\\\displaystyle{\cos \theta=0}\\\\\\\displaystyle{\cos \theta=\cos90}\\\\\\\displaystyle{\theta=90}

Thus we get answer.


Anonymous: Latex error:)
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