Class 12MathematicsTHREE DIMENSIONAL GEOMETRYSystem of co-ordinates, Direction cosines and direction ratios, Projection
MediumIf $a, b, c$ are the direction ratios of a line $L$ and $\ell, m, n$ are its direction cosines,then $\frac{a^2}{b^2+c^2}=$
- A$\frac{1-\ell^2}{\ell^2}$
- B$\frac{\ell^2}{1+\ell^2}$
- C$\frac{\ell^2}{\ell^2+m^2}$
- D$\frac{\ell^2}{1-\ell^2}$
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