(1)f(α)=cosα√[(1-sinα)²/(1-sin²α)+sinα√[(1-cosα)²/(1-cos²α)]=cosα√[(1-sinα)²/cos²α+sinα√[(1-cosα)²/sin²α]=cosα(1-sinα)/(-cosα)+sinα(1-cosα)/sinα=-1+sinα+1-cosα=sinα-cosα(2) f(α)=sinα-cosα=√2sin(α-π/4)当α=3π/4时,f(α)最大=√2