三角函数常用公式

n?9U !an?m?X 1.tanx = sinx cosx,cotx = 1 tanx,secx = 1 cosx,cscx = 1 sinx 2.sin2x + cos2x = 1,sec2x = tan2x + 1,csc2x = cot2x + 1 ?(1)?1 + sinx = sin2 x 2 + cos2 x 2 + 2sin x 2 cos x 2 = ?sin x 2 + cos x 2 ?2 (2)? u1 x2e?x = sint,t 2, 2K 1 x2 = p 1 sin2t = cost ?u1 + x2?x = tant,t ( 2, 2)K 1 + x2 = 1 + tan2 t = sect ?!?a 1.5?kksin(x + 2k) = sinx,cos(x + 2k) = cosx,tan(x + k) = tanx,cot(x + k) = cotx,sec(x + 2k) = secx,csc(x + 2k) = cscx 2.sin(x ) = sinx,cos(x ) = cosx,tan(x 2) = cotx C/sin( x) = sinx,cos( x) = cosx,tan( 2 x) = cotx 3.osin( 2 x) = cosx,sin( 2 + x) = cosx,cos( 2 x) = sinx,cos( 2 + x) = sinx 5p?qp?UL?rK? I?m n!? 1.sin( ) = sincos cossin 2.cos( ) = coscos sinsin 3.tan( ) = tantan 1tantan ?(1)sinx + cosx = 2h2 2 sinx + 2 2 cosx i = sin(x + 4) d1 cos(x 4) d2 (2)1+tanx 1tanx = tan(x + 4) 5|p-?!?z z?|y5 1 o!?!? 1.sin2x = 2sinxcosx 2.cos2x = cos2x sin2x = 2cos2x 1 = 1 2sin2x 3.tan2x = 2tanx 1tan2x 4.cos2 x 2 = 1+cosx 2 ,sin2 x 2 = 1cosx 2 5?u?k?O5gXcos3xsinx = cos2xcosxsinx = (1+cos2x 2 )1 2 sin2x = 1 4 sin2x + sin2xcos2x = 1 4 ?sin2x + 1 2 sin4x? !?z 1.sin + sin = 2sin + 2 cos 2 2.sin sin = 2cos + 2 sin 2 3.cos + cos = 2cos + 2 cos 2 4.cos cos = 2sin + 2 sin 2 5|?y?z5sin = sin(+ 2 + 2 )? ? 8!z? 1.sincos = 1 2sin( + ) + sin( ) 2.cossin = 1 2sin( + ) sin( ) 3.coscos = 1 2cos( + ) + cos( ) 4.sinsin = 1 2cos( + ) cos( ) !?U sin2x = 2ta