Question 19Find the value of $$\frac1{\sin^2 0.5^\circ}-\tan^2 0.5^\circ+\frac1{\sin^2 1.5^\circ}-\tan^2 1.5^\circ+\frac1{\sin^2 2.5^\circ}-\tan^2 2.5^\circ+\cdots+\frac1{\sin^2 179.5^\circ}-\tan^2 179.5^\circ.$$