已知f(阿尔法)=sin(π/2+α)+3sin(-π-α)/2cos(11π/2-α)-cos(5π-α).

问题描述:

已知f(阿尔法)=sin(π/2+α)+3sin(-π-α)/2cos(11π/2-α)-cos(5π-α).
(1)化简f(α) (2)已知tanα=3,求f(α)的值

1,f(α)=sin(π/2+α)+3sin(-π-α)/2cos(11π/2-α)-cos(5π-α).=(cosα-3sinα)/(-2sinα+cosα)f(α)=(cosα-3sinα)/(cosα-2sinα)2,tanα=3f(α)=(cosα-3sinα)/(cosα-2sinα)=(1-3tanα)/(1-2tanα)=(1-9)...