Find the value of p for which the vectors vec a = 3i +2j +9k vec b + I + pj +3k are (a) perpendicular (b) parallel
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if vec a and vec b is parallel then
vec a. vec b=0
(3i+2j+9k). (I+pj+3k) =0
or; 3+2p+27=0
or;30+2p=0
or;2p=-30
so p=-30/2=-15
vec a. vec b=0
(3i+2j+9k). (I+pj+3k) =0
or; 3+2p+27=0
or;30+2p=0
or;2p=-30
so p=-30/2=-15
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