Anyone here know any? I have a really hard time memorizing them >.<

- stapel_eliz
**Posts:**1731**Joined:**Mon Dec 08, 2008 4:22 pm-
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Do you perhaps mean "identities"...? Because there are infinitely-many "equations".

Try Googling "trig identities". Make sure you know the squaring equivalencies, the double- and half-angle identities, and the angle-sum and -difference identities. There are others, but those generally get the job done.

Try Googling "trig identities". Make sure you know the squaring equivalencies, the double- and half-angle identities, and the angle-sum and -difference identities. There are others, but those generally get the job done.