MCQ
$0.4\hat i + 0.8\hat j + c\hat k$ represents a unit vector when $c$ is
- A$-0.2$
- ✓$\sqrt {0.2} $
- C$\sqrt {0.8} $
- D$0$
✓
Answer
Correct option: B.
$\sqrt {0.2} $
b
(b) $\sqrt {{{(0.4)}^2} + {{(0.8)}^2} + {c^2}} = 1$
(b) $\sqrt {{{(0.4)}^2} + {{(0.8)}^2} + {c^2}} = 1$
==> $0.16 + 0.64 + {c^2} = 1$==> $c = \sqrt {0.2} $
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