tolong dong kakak kakak yang bisaa jawabb

vektor satuan jika panjangnya 1 satuan

akar((1/2)^2 + k^2 + (-1/4)^2) = 1
akar(1/4 + k^2 + 1/16) = 1
akar(4/16 + 1/16 + k^2) = 1
akar(5/16 + k^2) = 1
5/16 + k^2 = 1^2
5/16 + k^2 = 1
k^2 = 1 - 5/16
k^2 = 16/16 - 5/16
k^2 = 11/16
k = +_ akar(11/16) = +_ 1/4 akar11

jwb. D