If ¯a,¯b,¯c, are unit vector such that ¯a+¯b+¯c=¯0, then the ¯a.¯b+¯b.¯c+¯c.¯a=
A
32
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B
−32
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C
12
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D
−12
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Solution
The correct option is B−32 a,b,c,areunitVectorsuchthat→a+→b+→c=0(given)Then,⇒(→a+→b+→c)2=∣∣→a∣∣2+∣∣∣→b∣∣∣2+∣∣→c∣∣2+2(→a.→b+→b.→c+→c.→a)⇒0=1+1+1+2(→a.→b+→b.→c+→c.→a).−32=→a.→b+→b.→c+→c.→aAns.