高二数学课件苏教版高二三角函数高二数学课件

复习旧知识•两角和与差的正弦cossincossin)sin(cossincossin)sin(•两角和与差的正切sinsincoscos)cos(sinsincoscos)cos(•两角和与差的余弦tantan1tantan)tan(tantan1tantan)tan(讲授新课cossincossin)sin(sinsincoscos)cos(tantan1tantan)tan(cossincossin)sin(cossin22sinsinsincoscos)cos(22sincos2costantan1tantan)tan(2tan1tan22tan令cossin22sin22sincos2cos2tan1tan22tan二倍角公式)S(2)C(2)T(222sincos2cos1sincos2222sin1cos22cos1sin)cos1(cos221cos2222sin)sin1(2sin212sin212cos1cos22cos222cos1sin222cos1cos2公式左端的角是右端角的二倍在这两个公式中分别求出sin2a和cos2a灵活运用公式2cos2sin24sin2cos2sin2sin22sincos2coscossin22sin4xsin4xcos2xcos224xsin21214xcos22?8sin?21sin?3cos?6cos2sin212cos1cos22cos2.2tan,2cos,2sin,III,53sin8求设例,III,53sin解：2)53(12sin1cos54cossin22sin252422)53(21sin212cos25725725242cos2sin2tan724)54()53(2cossin22sin22sincos2cos2sin212cos1cos22cos2)10tan1(50sin900化简例)10cos10sin31(50sin)10tan1(50sin00000解：000010cos)10sin2310cos21(250sin00000010cos10sin30cos10cos30sin50sin2000010cos40sin)4090sin(20010cos80sin00010cos)1090sin(0010cos10cos1cossin22sin22sincos2cos2tan1tan22tan2sin212cos1cos22cos2