Question

If vector OA=4i+2j ,OB=6i-8j and OC=-2i+5j then find the value of <ACB.

Answer 1

vector AB = (2,-10)

vector CB = (8,-13)

vector AB (dot) vector CB
= |AB| |CB| cosØ , were Ø is angle ACB
16 + 130 = √104√233 cosØ
cosØ = .937903...
Ø = appr 20.3°