三角代换公式,如cos2x=1-2sinx*sinx,求更多,

sin2x=2sinxcosx cos2x=2cosx*cosx-1

cos2X=2cosx∧2－1

sinx平方+cosx平方=1
1+tanx平方=secx平方
1+cotx平方=cosec平方
sin2x=2sinxcox
cos2x=cosx平方-sinx平方
=2cosx平方-1
=1-2sinx平方
tan2x=2tanx/(1-tanx平方)
sin(a+b)=sina * cosb + cosa * sinb
sin(a-b)=sina * cosb - cosa * sinb
cos(a+b)=coa * cosb - sina * sinb
cos(a-b)=coa * cosb + sina * sinb
tan(a+b)=(tana +tanb)/1-tana * tanb
tan(a-b)=(tana -tanb)/1+tana * tanb
sina +sinb= 2 sin (a+b)/2 * cos(a-b)/2
sina - sinb= 2 cos(a+b)/2 * sin(a-b)/2
cosa + cosb =2 cos(a+b)/2 * cos(a-b)/2
cosa - cosb =2 sin(a+b)/2 * sin(a-b)/2
sinacosb=【sin(a+b) + sin(a-b)】/2
cosasinb=【sin(a+b) - sin(a-b)】/2
cosacosb=【sin(a+b) + sin(a-b)】/2
sinasinb= -【sin(a+b) - sin(a-b)】/2