Taking the det and equating it to 0 we get
tan θ = (q cos α - p cos β) / (q sinα - p sin β)
I think this the reqd condition
find the condition that the lines xcosα+ysinα=p,xcosβ+ysinβ=q and y=xtanθ may be concurrent?
Taking the det and equating it to 0 we get
tan θ = (q cos α - p cos β) / (q sinα - p sin β)
I think this the reqd condition