QR half and double angle identities???

[SFPredent]

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I just took Achiever 2 and it had a double angle ID problem. Has anyone seen these on the real DAT? I know the three squared IDs relating cos and sin, tan and cot, sec and csc, but didnt know the half and double identities. Thanks

 

[ldm0208]

I just took Achiever 2 and it had a double angle ID problem. Has anyone seen these on the real DAT? I know the three squared IDs relating cos and sin, tan and cot, sec and csc, but didnt know the half and double identities. Thanks

Searched and found this thread posted on july 06. Seems like he/she found no love from sdners. I actually see the double angle formula on destroyer as well. Anyone has a comment on this question? Thank you!!