A(→a), B(→b), C(→c) are the vertices of a triangle ABC and R(→r) is any point in the plane of triangle ABC, then →r.(→a×→b+→b×→c+→c×→a) is always equal to

A(→a), B(→b), C(→c) are the vertices of a triangle ABC and R(→

1.	A(→a), B(→b), C(→c) are the vertices of a triangle ABC and R(→r) is any point in the plane of triangle ABC, then →r.(→a×→b+→b×→c+→c×→a) is always equal to
Answer» $A (\to a), B (\to b), C (\to c)$ are the vertices of a triangle ABC and $R (\to r)$ is any point in the plane of triangle ABC, then $\to r . (\to a \times \to b + \to b \times \to c + \to c \times \to a)$ is always equal to