Question

Help with vectors?

How to determine the interior angles of ABC were A(5,1) B(4,-7) C(-1,-8)

I tried it but I didn't get the answer

Answer 1

the 3 vectors represent the position of 3 points.

if you create A-B and C-B you have two vectors with their tails at B

you can use (A-B) dot (C-B) to find the angle between these vectors

Answer 2

oh ok. Could you help with another problem

Answer 3

Did you get any answers for this one ?

Answer 4

hold on let me do it

Answer 5

i got 13 for (A-B) dot (C-B)

Answer 6

not -13 ?

Answer 7

no