When does two vectors equal magnitude have their resultant equal in magnitude of either of them?

When does two vectors equal magnitude have their resultant equal in ma

1.	When does two vectors equal magnitude have their resultant equal in magnitude of either of them?
Answer» SOLUTION :`R=sqrt(R^2+R^2+2R^2costheta),R^2+2R^2+2R^2costhetaR^2=2R^2(1+COSTHETA),1+costheta=1/2,costheta=(-1)/2,theta-120^@`