Hyperbola

A variable chord of the hyperbola (x^(2))/(a^(2))-(y^(2))/(b^(2))=1,(b>a), subtends a right angle at the center of the hyperbola if this chord touches.a fixed circle concentric with the hyperbola a fixed ellipse concentric with the hyperbola a fixed hyperbola concentric with the hyperbola a fixed parabola having vertex at (0,0).