(sina+cosa)^2=1/25
1+2sinacosa=1/25
sinacosa=-12/25
sina^4-cosa^4
(sina^2-cosa^2)(sina^2+cosa^2)
=(sina-cosa)(sina+cosa)*1
=-12/25*1/5
=-12/125
(sina+cosa)^2=1/25
1+2sinacosa=1/25
sinacosa=-12/25
sina^4-cosa^4
(sina^2-cosa^2)(sina^2+cosa^2)
=(sina-cosa)(sina+cosa)*1
=-12/25*1/5
=-12/125