Units and Measurements

The equation of a circle is given by $x^2+y^2=a^2$, where a is the radius. If the equation is modified to change the origin other than (0, 0), then find out the correct dimensions of A and B in a new equation : ${(x - At)^2} + {\left( {y - {t \over B}} \right)^2} = {a^2}$. The dimensions of t is given as $[\mathrm{T^{-1}]}$.