(a)
Given that, $xy = hx + ky$
$\Rightarrow (x - k)(y - h) = hk$
On shifting origin to $(k,\ h)$ the above equation reduces to
$XY = hk = c^{2}$ (say)
Where, $x = X + k$ and $y = Y + h$
Then, the equation of the asymptotes are $X = 0$ and $Y = 0\ ie,\ x = k,\ y = h$