The angle $\theta$ between the lines $a_1x + b_1y + c_1 = 0$ and $a_2x + b_2y + c_2 = 0$ is given by:

  • A
    $\tan^{-1} \left| \frac{a_1b_2 - a_2b_1}{a_1a_2 + b_1b_2} \right|$
  • B
    $\tan^{-1} \left| \frac{a_1b_2 - a_2b_1}{a_1a_2 + b_1b_2} \right|$
  • C
    $\cot^{-1} \left| \frac{a_1a_2 + b_1b_2}{a_1b_2 - a_2b_1} \right|$
  • D
    $\tan^{-1} \left| \frac{a_1b_1 - a_2b_2}{a_1a_2 + b_1b_2} \right|$

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