-5*6/-5-7=-30/-12=2целых 1вторая (2,5)
(tg²α-sin²α)/(cos²α-ctg²α)=(sin²α/cos²α-sin²α)/(cos²α-cos²α/sin²α)=
=((sin²α*-sin²α*cos²α)/cos²α)/((sin²α*cos²α-cos²α)/sin²α)=
=(sin²α*(1-cos²α))/cos²α)/(cos²α*(sin²α-1))/sin²α)=(sin⁴α/cos²α)/(cos⁴α/sin²α)=
=sin⁶α/cos⁶α=tg⁶α.