ΔABC with all acute angles is given. The point whose coordinates are (cosB-sinA sinB-cosA) can be in which quadrant
The abscissa of 2 points A and B are the roots of the equation x^2+2x-a^2=0 and the ordinate are the roots of the equation y^2+4y-b^2=0. Find the equation of the circle with AB as a diameter.