If `| vec a|=| vec b|,\ t h e n\ ( vec a+ vec b)dot( vec a- vec b)=` a. positive b. negative c. `0` d. none of these

Find | vec a| and | vec b| , if ( vec a+ vec b)dot(( vec a- vec b))=8 and |vec a|=8 | vec b|

Find | vec a|a n d\ | vec b| , if : ( vec a+ vec b)dot'( vec a- vec b)=8\ a n d\ | vec a|=8| vec b|

Find | vec a|a n d\ | vec b| , if : ( vec a+ vec b)dot'( vec a- vec b)=12\ a n d\ | vec a|=2| vec b|

Find | vec a|a n d\ | vec b| , if : ( vec a+ vec b)dot'( vec a- vec b)=13\ a n d\ | vec a|=2| vec b|

Find | vec a|a n d| vec b|,if( vec a - vec b)dot ( vec a+ vec b) =27 and | vec a|=2| vec b|dot

If vec a ,\ vec b ,\ vec c are three non-zero vectors, no two of which are collinear and the vector vec a+ vec b is collinear with vec c ,\ vec b+ vec c is collinear with vec a ,\ t h e n\ vec a+ vec b+ vec c= vec a b. vec b c. vec c d. none of these

If vec d= vec axx vec b+ vec bxx vec c+ vec cxx vec a is non-zero vector and |( vec d * vec c)( vec axx vec b)+( vec d* vec a)( vec bxx vec c)+( vec d*vec b)( vec cxx vec a)|=0, then a. | vec a|=| vec b|=| vec c| b. | vec a|+| vec b|+| vec c|=|d| c. vec a , vec b ,a n d vec c are coplanar d. none of these

If vec d= vec axx vec b+ vec bxx vec c+ vec cxx vec a is non-zero vector and |( vec d * vec c)( vec axx vec b)+( vec d* vec a)( vec bxx vec c)+( vec d*vec b)( vec cxx vec a)|=0, then a. | vec a|=| vec b|=| vec c| b. | vec a|+| vec b|+| vec c|=|d| c. vec a , vec b ,a n d vec c are coplanar d. none of these

If vec d= vec axx vec b+ vec bxx vec c+ vec cxx vec a is non-zero vector and |( vec d * vec c)( vec axx vec b)+( vec d* vec a)( vec bxx vec c)+( vec d*vec b)( vec cxx vec a)|=0, then a. | vec a|=| vec b|=| vec c| b. | vec a|+| vec b|+| vec c|=|d| c. vec a , vec b ,a n d vec c are coplanar d. none of these

If vec b is a unit vector such that ( vec a+ vec b)dot ( (vec a- vec b))=8,\ find \ | vec a|dot