Question

If A vector+B vector=C vector &C vector=13 units &A vector× B vector=13.5 units then angle between A vector & B vector is
​

Answer 1

Answer:

∣a−b∣

2

+∣b−c∣

2

+∣c−a∣

2

=2(a

2

+b

2

+c

2

)−2(a.b+b.c+c.a)

=2×3−2(a.b+b.c+c.a)

=6−{(a+b+c)

2

−a

2

−b

2

−c

2

}

=9−∣a+b+c∣

2

≤9