1.
If m1m_1 and m2m_2 are slopes of the lines represented by (sec2θsin2θ)x22tanθxy+sin2θy2=0(\sec^2 \theta - \sin^2 \theta)x^2 - 2\tan\theta \, xy + \sin^2\theta \, y^2 = 0, then m1m2|m_1 - m_2| is