cotx=

(quotient identity)

x

x

sin

cos

Answer

sinxcosx=

x2sin2

1

Answer

tan(x/2)=

(half angle identity)

2tan1

2tan2

2 x

x

Answer

tan(x+y)=

(sum identity)

yx

yx

tantan1

tantan

Answer

sin(x+y)=

(sum identity)

=sinxcosy+sinycosx

Answer

cos(2x)=

(double angle identity)

=cos2x-sin2x (main-others are found using Pythagorean Identities)

=2cos2x-1=1-2sin2x

Answer

sin(x/2)=

(half angle identity)

2cos

2sin2

xx

Answer

sinx=

(reciprocal identity)

xcsc

1

Answer

cot2x=

(Pythagorean identity)

=csc2x-1

Answer

tanx=

(reciprocal identity)

xcot

1

Answer

cos(x+y)=

(sum identity)

=cosxcosy-sinxsiny

Answer

sin(x-y)=

(difference identity)

=sinxcosy-sinycosx

Answer

sin2x=

(Pythagorean identity)

=1-cos2x

Answer

cos(x/2)=

(half angle identity)

2sin21

12

cos2

2sin

2cos

2

2

22

x

x

xx

Answer

tanx=

(quotient identity)

x

x

cos

sin

Answer

tan2x+1=

(Pythagorean identity)

=sec2x

Answer

tan(2a)=

(double angle identity)

x

x2tan1

tan2

Answer

cos(x-y)=

(difference identity)

=cosxcosy+sinxsiny

Answer

sin(2x)=

(double angle identity)

=2sinxcosx

Answer

tan(x-y)=

(difference identity)

yx

yx

tantan1

tantan

Answer

cosx=

(reciprocal identity)

xsec

1

Answer