RheBA wrote:

azn099 wrote:

i really doubt i'll get a good answer here but meh i'll try.

anybody have any easy ways to memorize trigonometric identities? double-angle and half-angle identities are the ones i haven't got down yet. i know the pythagorean relationships and sum/difference identities already.

if u know the additon formulae then double angle shud not b a prob...

eg. sin(A+B) = sinAcosB+cosAsinB

then the double formulae would b...

sin2A = sin (A+A)

= sinAcosA+cosAsinA

= 2sinAcosA

sumhow i doubt i'm helping...

i know that, and i would do that. however for part 1 of my math test we need to write all the identites in a limited amount of time, so writing out a proof like that would take me too long.

what i mean is a saying or something to help me remember it easier.

like for the pythagorean relationship

1+tan^2x=sec^2x

my teacher taught me "i love tangerine sections." it's kind of cheesy, but it helps me remember it easier.