I created this free printable trig identities cheat sheet for my Pre-Calculus students to reference as we work through our unit on trigonometric identities.
I do not require my pre-calc students to memorize the various trig identities. I am more interested in my students being able to use and apply trig identities than to be able to recite them from memory.
The reference sheet I use with my students includes reciprocal identities, quotient identities, pythagorean identities, and negative angle identities.
They also reference our trig identities cheat sheet while working on worksheets including my Verifying Trig Identities Worksheet, One or Negative One Trig Identities Worksheet, and Double Angle Identities Joke Worksheet.