Let ABC be a triangle formed by the lines 7x−6y+3=0,x+2y−31=0 and 9x−2y−19=0, Let the point (h,k) be the image of the centroid of △ABC in the line 3x+6y−53=0. Then h2+k2+hk is equal to
(A)37✓ Correct
(B)47
(C)40
(D)36
Answer: (A)
Solution
Solving the lines pairwise gives the vertices of the triangle: 7x−6y+3=0 with x+2y−31=0 gives A(9,11); x+2y−31=0 with 9x−2y−19=0 gives B(5,13); 9x−2y−19=0 with 7x−6y+3=0 gives C(3,4).