0.4i +0.8 j + ck represents a unit vector explain why c is under root 0.2
Unit Vector means the modulus should be 1. Let the Vector be X.
Hence, |X|= (0.4*0.4+0.8*0.8+c*c)^0.5
Where |X|=1
Hence on Squaring Both Sides and Solving we get
c= (0.2)^0.5
It means Component of the Vector in z direction, extends a distance of square root of 0.2 .
If the angle made by the Unit Vector X and the z axis is ×, then |X| Cos× is square root of 0.2 .