Question

the three vectors oa ob and oc have the same magnitude R then the sum of these vectors have magnitude

Answer 1

Polygon law of vector addition states that, "If the magnitude and directions of a number of vectors can be represented by the sides of the polygon, then the resultant vector is represented by the magnitude and direction of the polygon taken in the opposite order".

According to this law, if $R_1, R_2$ and $R_3$ are the magnitudes of the three vectors, then the resultant vector R is given by,                                          

                                         $R_1+R_2+R_3$