Help please Найти угол между двумя прямыми 5x-y+7=0 и 2x-3y+1=0
5x-y+7=0 2x-3y+1=0 α=? y=5x+7 y=(2/3)x+1/3 tgα=(2/3-5)/(1+5*(2/3))=(-4¹/₃)/(1+5*(2/3)=(-13/3)/(1+10/3)=(-13/3)/(13/3)=-1 α₁=3π/4=135° α₂=7π/4=315°.