[A,B,C&D" are four points in a plane wit...

[A,B,C&D" are four points in a plane with "],[pv'svec a,vec b,vec c&vec d" respectively such that "],[(vec a-vec d)(vec b-vec c)=(vec b-vec d)(vec c-vec a)=0." Then for "],[" the triangle "ABC,D" is its: "],[[" (A) incentre "," (B) circumcentre "],[" (C) orthocentre "," (D) centroid "]]

[A,B,C&D" are four points in a plane with "],[pv'svec a,vec b,vec c&vec d" respectively such that "],[(vec a-vec d)*(vec b-vec c)=(vec b-vec d)*(vec c-vec a)=0." Then for "],[" the triangle "ABC,D" is its: "],[[" (A) incentre "," (B) circumcentre "],[" (C) orthocentre "," (D) centroid "]]