Show that every normal to the curve will always pass through the point (0,0).
I have no idea how to approach this question. Could someone explain it to me please?
If you are allowed to demonstrate this graphically, you'll see that the function is a circle with center at the origin and radius a.
So at every point on the circle, the normal (line perpendicular to the tangent at point (a, f(a))) , will pass through the origin.