Respuesta :

So first you have to know the distance between those three points:

AB= √18

BC= 5

AC=√13

Then use Trigonometric function to find m/_ABC:

CosB=(a^2+c^2-b^2)/2ac

cosB={(√18)^2+(√13)^2-5^2}/2√18√13

The Answer should be m/_ABC=30