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# preap precalculus

### trig identities

sinx 1/cscx
cosx 1/secx
sin^2x + cos^2x 1
tan^2x + 1 sec^2x
1 + cot^2x csc^2x
sin(-x) -sinx [odd]
csc(-x) -cscx [odd]
cos(-x) cosx [even]
sec(-x) secx [even]
tan(-x) -tanx [odd]
cot(-x) -cotx [odd]
sinx (cofunction) cos(pi/2 - x)
tanx (cofunction) cot(pi/2 - x)
secx (cofunction) csc(pi/2 - x)
sin(x+y) sinxcosy + cosxsiny
sin(x-y) sinxcosy - cosxsiny
cos(x+y) cosxcosy - sinxsiny
cos(x-y) cosxcosy + sinxsiny
tan(x+y) (tanx + tany)/(1 - tanxtany) OR sin(x+y)/cos(x+y)
tan(x-y) (tanx - tany)/(1 + tanxtany) OR sin(x-y)/cos(x-y)
sin2x 2sinxcosx
cos2x cos^2x - sin^2x OR 2cos^x - 1 OR 1 - 2sin^2x
tan2x 2tanx/(1 - tan^2x) OR sin2x/cos2x
sin(x/2) +-sqrt (1-cosx)/2
cos(x/2) +-sqrt (1+cosx)/2
tan(x/2) (1-cosx)/sinx OR sinx/(1+cosx)
sin^2a (1-cos2a)/2
cos^2a (1+cos2a)/2
tan^2a sin^2a/cos^2a OR (1-cos2a)/(1+cos2a)
Created by: qiguai

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