Vertices of a variable acute-angled triangle ABC lie on a circle of radius R such that da/dA + db/dB + dc/dC = 6. Distance of orthocentre of triangle ABC from vertices A, B and C is x1, x2 and x3, respectively
1. In-radius of triangle ABC is
(A) 1
(B) 2
(C) 3
(D) 4
2. Maximum value of x1x2x3 is
(A) 4
(B) 6
(C) 8
(D) 10
3. dx1/da + dx2/db + dx3/dc is always less than equal to
(A) -3√3
(B) 3√3
(c) 1
(D) 6