sin(a+b)= Sina cosb+cosasinbsin(a-b)= Sina cosb-sinbcosa

cos(a+b)= cosa cosb-Sina sinb cos(a-b)= cosa cosb+Sina sinb

tan(a+b)=(tana+tanb)/( 1-tana tanb)tan(a-b)=(tana-tanb)/( 1+tana tanb)

Double angle formula

tan2a = 2 tana/( 1-tan2a)ctg2a =(ctg2a- 1)/2c TGA

cos2a = cos2a-sin2a = 2 cos2a- 1 = 1-2 sin2a

half-angle formula

sin(a/2)=√(( 1-cosa)/2)sin(a/2)=-√(( 1-cosa)/2)

cos(a/2)=√(( 1+cosa)/2)cos(a/2)=-√(( 1+cosa)/2)

tan(a/2)=√(( 1-cosa)/(( 1+cosa))tan(a/2)=-√(( 1-cosa)/(( 1+cosa))

ctg(a/2)=√(( 1+cosa)/(( 1-cosa))ctg(a/2)=-√(( 1+cosa)/(( 1-cosa))

Sum difference product

2 Sina cosb = sin(a+b)+sin(a-b)2 cosa sinb = sin(a+b)-sin(a-b)

2 cosa cosb = cos(a+b)-sin(a-b)-2 sinasinb = cos(a+b)-cos(a-b)

Sina+sinb = 2 sin((a+b)/2)cos((a-b)/2 cosa+cosb = 2 cos((a+b)/2)sin((a-b)/2)

tana+tanb = sin(a+b)/cosacosbtana-tanb = sin(a-b)/cosacosb

ctga+ctgbsin(a+b)/Sina sinb-ctga+ctgbsin(a+b)/Sina sinb