A straight line `L` on the xy-plane bisects the angle between `O Xa n dO Ydot` What are the direction cosines of `L ?` a. `<<(1//sqrt(2)),(1//sqrt(2)),0>>` b. `<<(1//2),(sqrt(3)//2),0>>` c. `<<0,0,1>>` d. `<<(2//3),(2//3),(1//3)>>`