If the vertices A,B,C of a triangle ABC are (1, 1, 3), (-1, 0, 0),(0, 1, 2) respectively, then determine ∠ABC. (∠ABC is the angle between the vectors and )

Question

Question

This question was previously asked in

AAI ATC Junior Executive 25 March 2021 Official Paper (Shift 1)

Answer 1

Given:

The vertices A,B,C of a triangle ABC are (1, 1, 3), (-1, 0, 0), (0, 1, 2) respectively.

Concept:

= p.v.() - p.v.()

Formula:

The angle between two vectors and is given by :

Solution:

= (1, 1, 3) - (-1, 0, 0)

= 2î + ĵ + 3k̂

= (0, 1, 2) - (-1, 0, 0) = î + ĵ + 2k̂

∴

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