Four distinct points (2k,3k),(1,0),(0,1) and (0,0) lie on a circle for k equal to :
- 313
- 213
- 513
- 113
Answer
(3) 513
Solution
AOB=90 AB is a diameter of the circle through O, A, B
[figure]
Circle: x(x-1)+y(y-1)=0, i.e. x2+y2-x-y=0
(2k,3k) on it: 13k2-5k=0 k=0 or 513
k=0 gives (0,0) again (points are distinct) k= 513
Answer: (3)