A) 23
B) 7
C) 17
D) 18
Correct Answer: B
Solution :
Since,\[|\vec{a}|=5,|\vec{b}|=3\]and angle between \[\vec{a}\]and\[\vec{b}\]is \[\frac{2\pi }{3}.\] \[\therefore \] \[|\vec{a}-\vec{b}{{|}^{2}}=|\vec{a}{{|}^{2}}+|\vec{b}{{|}^{2}}-2|\vec{a}||\vec{b}|cos\frac{2\pi }{3}\] \[={{5}^{2}}+{{3}^{2}}-2.5.3\left( -\frac{1}{2} \right)\] \[25+9+15\] \[=49\] \[\,\Rightarrow \] \[|\vec{a}-\vec{b}|=7\]You need to login to perform this action.
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