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)/(1-6)=8/5
