Topics:

  • Pythagorean identities
  • cofactor identities
  • odd/even identities
  • sum/difference identities
  • examples:
    • $\sin(x+\frac{\pi}{2}) = \cos x$
    • $-\tan(x-\frac{\pi}{2}) = \cot x$
    • $\frac{\cos x}{1-\sin x} = \sec x + \tan x$

Reference: OSP 7.1, 7.2

notes (pdf)