(1+tanα)／(1-tanα)=20061+tanα=2006(1-tanα)tanα=2005/2007cos2α=(1-tan^2α)/(1+tan^2α)=(1-2005^2/2007^2)/(1+2005^2/2007^2)tan2α=2tanα/(1-tan^2α)=(2*2005/2007)/(1-2005^2/2007^2)1／cos2α+tan2α...