3-1.Vectors
easy

किसी सदिश के प्रारंभिक तथा अंतिम बिन्दुओं के निर्देशांक $(4, -4, 0) $ तथा $(-2, -2, 0)$ हैं। इसका परिमाण होगा

A

$6$

B

$5\sqrt 2 $

C

$4$

D

$2\sqrt {10} $

Solution

(d) $\mathop r\limits^ \to = {\mathop r\limits^ \to _2} – {\mathop r\limits^ \to _1} = ( – 2\hat i – 2\hat j + 0\hat k) – (4\hat i – 4\hat j + 0\hat k)$

$⇒$ $\mathop r\limits^ \to = – 6\hat i + 2\hat j + 0\hat k$

 $\therefore |\mathop r\limits^ \to | = \sqrt {{{( – 6)}^2} + {{(2)}^2} + {0^2}} = \sqrt {36 + 4} = \sqrt {40} = 2\sqrt {10} $

Standard 11
Physics

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