If the vertices A, B, C of a triangle ABC are `(1, 2, 3), (1, 0, 0), (0, 1, 2)`, respectively, then
Channel: Doubtnut
Date: 2020-07-05

If the vertices A, B, C of a triangle ABC are `(1, 2, 3), (1, 0, 0), (0, 1, 2)`, respectively, then find `/_A B C`. [`/_A B C`is the angle between the vectors ` vec( B A)`and ` vec (B C)`.