Mach the following 

If the pair of straight lines joining the origin to the common points of x² +y² =9 and y = x + C are perpendicular then c is equal to 

The lines joining the origin to the points of intersection of   and  are perpendicular then c is equal to 

If the straight lines joining the origin to the points of intersection of the line  and the curve  are perpendicular then m equals to

If y = 3x bisects the angle between the lines  then a equals to

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