I am currently taking Calc II and we are doing trig substitutions at the moment. I seem to have forgotten almost all the important trig identities. I understand that this sounds like something I should google but I honestly cannot find a good list of the trig identities I should know at this point. If someone could help me with the trig identities that I should memorize I would appreciate it. Thank you. Edit: An example would be sin(2x)=2sin(x)cos(x) or tan2(x)=sec2(x)-1. Those are two I remember but I know I am forgetting a ton.