indeed it is a good quesion but i have one doubt
suppose we shift our origin to the centre of the hyperbola which is (2,0)
now the equations 3x-4y-6=0
becomes 3X - 4Y = 0.........................(X,Y ) are the new co-ordiante axes
on comparing this with
X/a (+ -) Y/b =0
we get a = 1/3 and b = 1/4
but since it is rectangular a should be equal to b but we can see it is not .
so why is this contradiction .
someone plzzzzzzzzzz. help