The angle between the lines 2x-y+3=0 and x+2y+3=0 is
(1)
Given equations of lines are
2x-y+3=0; m1=slope=2
x+2y+3=0; m2=slope=-12
So, tanθ=|m1-m21+m1m2|=|2+121-1|=52×0=50=∞
⇒ tanθ=tanπ2⇒θ=π2