Class 12MathematicsThree Dimensional GeometrySystem of co-ordinates, Direction cosines and direction ratios, Projection
EasyWhich of the following statements is false?
- A$1$. If $(a, b, c)$ are direction ratios of a line,then $a^2+b^2+c^2 \neq 1$.
- B$2$. The direction cosines of a line can be its direction ratios but not vice-versa.
- C$3$. If $(l, m, n)$ is one set of direction cosines,then $(-l, -m, -n)$ is also a valid set.
- D$4$. If $(l_1, m_1, n_1)$ and $(l_2, m_2, n_2)$ are direction cosines of perpendicular lines,then $l_1 l_2+m_1 m_2+n_1 n_2=1$.
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