(sinx-1)tanx怎么化简成[(sinx-sinπ/2)/sin(x+π/2)]sinx,x趋于π/2

问题描述:

(sinx-1)tanx怎么化简成[(sinx-sinπ/2)/sin(x+π/2)]sinx,x趋于π/2

(sinx-1)tanx=(sinx-sinπ/2)tanx=(sinx-sinπ/2)(sinx/cosx)
注意sin(x-π/2)=cosx