Trig identities

[juswanthatDDS]

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what trig identities are a must to have memorized? i have kinda just skimmed over them but i want to memorize the ones that are known to be essential thanks

 

[aznriptide859]

Pretty much know:

45-45-90 triangles (along with sides)
30-60-90 triangles (along with sides)

And cos, sin, and tan (or the common mnemonic SOHCAHTOA).

Pretty much every other trig function/identity/value can be derived from these simple reference triangles. Of course, it doesn't hurt to remember some of them (such as sin^2(x) + cos^2(x) = 1).

 

[darkkings13]

would we have to memorize the unit circle?

 

[aznriptide859]

If you're into memorizing large amounts of numbers, then sure go ahead. But you can derive pretty much any of the unit circle values via the 45-45-90 and 30-60-90 triangles.