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Let `veca and vecb` be unit vectors such that `|veca+vecb|=sqrt3`. Then find the value of `(2veca+5vecb).(3veca+vecb+vecaxxvecb)` |
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Answer» `(2veca+5vecb).(3veca+vecb+vecaxxvecb)=6veca.veca+17veca.vecb+5vecb.vecb=11+17veca.vecb` `(veca.(vecaxxvecb)=vecb.(vecaxxvecb)=0,as veca and vecb` are perpendicular to `veca xx vecb`) `|veca+vecb|=sqrt3` `|veca+vecb|^(2)=3` `|veca|^(2)+|vecb|^(2)+2veca.vecb=3` `veca.vecb=1/2` `Rightarrow (2veca+5vecb).(3veca+vecb+veca xx vecb)11+17/2=39/2` |
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