The resultant of the three vectors →OA,→OB and →OCshown in figure is,
r(1+√2)
O→C and O→A are equal in magnitude and inclined to each other at an angle of 900. So, their resultant is√2r.Its acts mid-way between O→CandO→A,i.e.,along OB. Now, both r and √2 r are along same line and in the same direction. ∴Resultant r+√2r=r(1+√2)