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AP EAMCET · Maths · Three Dimensional Geometry

If \(\mathrm{a}, \mathrm{b}, \mathrm{c}\) are the direction ratios of a line \(\mathrm{L}\) and \(\ell, m, n\) are its direction cosines, then \(\frac{a^2}{b^2+c^2}=\)

  1. A \(\frac{1-\ell^2}{\ell^2}\)
  2. B \(\frac{\ell^2}{1+\ell^2}\)
  3. C \(\frac{\ell^2}{\ell^2+m^2}\)
  4. D \(\frac{\ell^2}{1-\ell^2}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\frac{\ell^2}{\ell^2+m^2}\)

Step-by-step Solution

Detailed explanation

Let \(\mathrm{a}=\frac{1}{\mathrm{k}}, \mathrm{b}=\frac{\mathrm{m}}{\mathrm{k}}\) and \(\mathrm{c}=\frac{\mathrm{n}}{\mathrm{k}}\)…