Buktikan bahwa identitas cos x sec x – cos²x = sin²x

cos x sec x – cos² x = sin² x
cos x 1/(cos x) – cos² = sin² x
1 – cos² x = sin² x
sin² x = sin² x

Terbukti.

Cosx secx – cos²x
= cosx(1/cos) – cos²x
= 1 – cos²x
= sin²x ← terbukti