Straight Lines And Pair Of Straight Lines

Assertion (A) The difference of the slopes of the lines represented by $y^2-2 x y \sec ^2 \alpha+\left(3+\tan ^2 \alpha\right)$ $\left(-1+\tan ^2 \alpha\right) x^2=0$ is 4

Reason (R) The difference of the slopes represented by $a x^2+2 h x y+b y^2=0$ is $\frac{2 \sqrt{h^2-a b}}{|b|}$