Hi guys.. I was just solving a problem related to parabolas and came across this situation.Everything I did seems right but there seems to be a mistake somewhere. Here goes the situation
There is a parabola (x-y)^2 = -48(x+y+4). So I figured that the axis must be x-y=0 and the tangent at the vertex must be x+y+4=0.So the vertex should be (-2,-2). Using the value of 'a' that is 8, I figured that the directrix should be 8 units away from the tangent at the vertex(this is because if you tilt the axes so that the axis of the parabola becomes the y axis,the distance between the tangent at the vertex and directrix must be 8.So even if I again tilt the axes back to the original position the distance between them remains the same) and found it to be x+y-4=0.So the point where the directrix intersects the axis is (2,2). Now comes the interesting part.When I found the distance between (2,2) and(-2.-2) it was not 8.I am shocked. I found the directrix taking the distance to be 8.But why isn't the distance not 8?