(sinˇ4(α)-cosˇ4(α))/(sin²α+cos²α)(sin²α-cos²α)/(sinα-cosα)=(sinα+cosα)(sinα-cosα)/(sinα-cosα)=sinα+cosα
/sin²α+cos²α=1, sin²α-cos²α=(sinα+cosα)(sinα-cosα)/
(sinˇ4(α)-cosˇ4(α))/(sin²α+cos²α)(sin²α-cos²α)/(sinα-cosα)=(sinα+cosα)(sinα-cosα)/(sinα-cosα)=sinα+cosα
/sin²α+cos²α=1, sin²α-cos²α=(sinα+cosα)(sinα-cosα)/