The angle between the lines a1x + b1y + c1 = 0 and a2x + b2y + c2 =0, is
1
\({\tan ^{ - 1}}\frac{{{a_1}{b_2} + {a_2}{b_1}}}{{{a_1}{a_2} - {b_1}{b_2}}}\)
2
\({\cot ^{ - 1}}\frac{{{a_1}{a_2} + {b_1}{b_2}}}{{{a_1}{b_2} - {a_2}{b_1}}}\)
3
\({\cot ^{ - 1}}\frac{{{a_1}{b_1} - {a_2}{b_2}}}{{{a_1}{a_2} + {b_1}{b_2}}}\)
4
\({\tan ^{ - 1}}\frac{{{a_1}{b_1} - {a_2}{b_2}}}{{{a_1}{a_2} + {b_1}{b_2}}}\)
5
Question Not Attempted