Unit Vector 0.4i+0.8j+ck when represents a unit vector when c is

Q. \(0.4\hat{i}+0.8\hat{j}+c\hat{k}\) represents a unit vector when c is

1) -0.2

2) √0.2

3) √0.8

4) 0

Answer:

2) √0.2

Solution:

\(\sqrt{(0.4)^{2}+(0.8)^{2}+c^{2}} = 1\)

= 0.16 + 0.64 +c²

= 1

= \(c = \sqrt{0.2}\)