The x-coordinate of the incentre of the triangle that has the coordinates of mid points of its sides as (0,1)(1,1) and (1,0) is
(A)2−2✓ Correct
(B)1+2
(C)1−2
(D)2+2
Answer: (A)
Solution
The midpoints (0,1),(1,1),(1,0) belong to a triangle whose vertices are twice removed: (0,0),(2,2),(0,2). Its side lengths are a=22 opposite (0,0), and b=c=2 opposite the other two. The incentre's x-coordinate is a+b+cax1+bx2+cx3=22+422⋅0+2⋅2+2⋅0=4+224, which rationalises to 2−2.
JEE Main · 2013 · 07 Apr 2013 · Offline · Single correct option