trigonometry formula

sum and difference formula, double angle formula, half angle formula, product to sum formula, sum to product formula

cos(a+b)

cosacosb-sinasinb

cos(a-b)

cosacosb+sinasinb

sin(a+b)

sinacosb+cosasinb

sin(a-b)

sinacosb-cosasinb

tan(a+b)

(tana+tanb)/(1-tanatanb)

tan(a-b)

(tana-tanb)/(1+tanatanb)

sin(2x)

2sinxcosx

cos(2x)

cos²x-sin²x

cos(2x)

2cos²x-1

cos(2x)

1-2sin²x

tan(2x)

(2tanx)/(1-tan²x)

sin(x/2)

plusminusroot(1-cosx)/2

cos(x/2)

plusminusroot(1+cosx)/2

tan(x/2)

plusminusroot(1-cosx)/(1+cosx)

tan(x/2)

plusminus(1-cosx)/sinx

tan(x/2)

plusminussinx/(1+cosx)

sinasinb

1/2(cos(a-b)-cos(a+b))

cosacosb

1/2(cos(a-b)+cos(a+b))

sinacosb

1/2(sin(a+b)+sin(a-b))

sina+sinb

2sin((a+b)/2)cos((a-b)/2)

sina-sinb

2sin((a-b)/2)cos((a+b)/2)

cosa+cosb

2cos((a+b)/2)cos((a-b)/2)

cosa-cosb

-2sin((a+b)/2)sin((a-b)/2)