1. The problem statement, all variables and given/known data Prove that the straight line x cos @ + y sin @ = p is a tangent to the ellipse x2/a2 + y2/b2 if a2 cos2@ + b2 sin2@ =p2 . u and v are the perpendicular distances of a tangent from the two points M(0,ae) and N(0,-ae) respectively. Prove that u2 + v2 is a constant. 2. The attempt at a solution So far I have: xx1/a2+yy1/b2 -1 = x cos@ + y sin@ - p I don't know where to go from here and I know in the second part I have to use the perpendicular distance formula but I'm not sure what to sub in and why.