首页 > 留学知识库

问题: 如何转换的?

SIN(X+B)-SINX是如何转换成2COX(X+B/2)SIN(B/2)?

能否给出详细过程?

解答:

sin(x+b)-sinx=sinxcosb+cosxsinb -sinx
=sinx(cosb-1)+cosxsinb
=-sinx*2(sinb/2)^2+cosxsinb
=-sinx*2(sinb/2)^2+cosx*2cosb/2sinb/2
=2sinb/2(cosxcosb/2-sinxsinb/2)
=2sinb/2cos(x+b/2)