if `bar(a) + bar(b) + bar(c ) = bar(0), |bar(a)| = 3, |bar(b)| = 5, |bar(c )| = 7` then find angle between `bar(a) , bar(b)`.

If |bar(a)+bar(b)| = |bar(a)-bar(b)| then find the angle between bar(a) and bar(b) .

If bar(a) is a perpendicular to bar(b) and bar(c), |bar(a)|=2, |bar(b)|=3, |bar(c)|=4 and the angle between bar(b) and bar(c) is (2pi)/(3) then |[bar(a) bar(b) bar(c)]| =

If |bar(a).bar(b)| = |bar(a) xx bar(b)| & bar(a). bar(b) lt 0 , then find the angle between bar(a) and bar(b) .

bar(a) , bar(b) and bar(c) are three vectors such that bar(a) + bar(b) + bar(c) = bar(0) and |bar(a)| =2, |bar(b)| =3, |bar(c)| =5 ,then bar(a) . bar(b) + bar(b) . bar(c) + bar(c) . bar(a) equals

If |bar(a) xx bar(b)|= bar(a).bar(b) , then find the angle between the vectors bar(a) and bar(b) .

If |bar(a).bar(b)|=3 and |bar(a)xx bar(b)|=4 then the angle between bar(a) and bar(b) is ………………