The condition that the chord `xcosalpha+ysinalpha-p=0` of `x^2+y^2-a^2=0` may subtend a right angle at the center of the circle is

The condition that the chord x cos alpha+y sin alpha=p of x^(2)+y^(2)=a^(2) may subtend a right angle at the centre is a^(2)=lambda p^(2) then lambda is

If the chord x cos alpha+y sin alpha=p of the hyperbola (x^(2))/(16)-(y^(2))/(18)=1 subtends a right angle at the center,and the diameter of the circle, concentric with the hyperbola,to which the given chord is a tangent is d, then the value of (d)/(4) is

The normal chord of the parabola y^(2)=4ax subtends a right angle at the focus.Then the end point of the chord is

The locus of the midpoint of the chord of the circle x^2 + y^2 =4 which subtends a right angle at the origin is?

If the chord joining the points (2,-1),(1,-2) subtends a right angle at the centre of the circle,then its centre and radius are