Trigonometry Question

[superjags99]

How do you simplify the expression (1 � sec q)(1 + sec q).? q = theta
i'm taking an online trig class and the movies they give you don't help out at all.

[nescio]

(1-sec q)(1+sec q) = 1- sec^2 q = - tan^2 q.

movies ??? the mind boggles !