there was some confusion with the gradient thing lol
m(norm. P) = -1/t
.: m(norm. Q) = t
.: m(tang. Q) = -1/t
dy/dx = x/2a
For the point of contact of tangents with gradient -1/t
-1/t = x/2a
x = -2a/t
y = 2a/t^2
Q[-2a/t, 2a/t^2]
(in my previous try, i subbed in dy/dx as gradient of...