сosB=sinA=10/109(ko..)
sinA=(ko..)1-cosA=(ko..1-(10/109)^2)=7/(ko..109)
tgA=sinA/cosA=(7/ko..109)/(10/ko..109)=7/10
(6х-10у)•(6х+10у)-36х2= 36х+60ху-60ух-100-36х2=3•3•0.1-100-3•2=0.9-100•6=0.9-600=599.1