If →a,→b and →c are unit vectors satisfying |→a−→b|2+|→b−→c|2+|→c−→a|2=9, then |2→a+5→b+5→c|=

If →a,→b and →c are unit vectors satisfying |→a−→b|2+|→b

1.	If →a,→b and →c are unit vectors satisfying \|→a−→b\|2+\|→b−→c\|2+\|→c−→a\|2=9, then \|2→a+5→b+5→c\|=
Answer» If $\to a, \to b$ and $\to c$ are unit vectors satisfying $\| \to a - \to b \|^{2} + \| \to b - \to c \|^{2} + \| \to c - \to a \|^{2} = 9,$ then $\| 2 \to a + 5 \to b + 5 \to c \| =$