Question 1006181
Use distance formula to get values for the lengths of AB, AC, BC.  Use Law Of Cosines to find the unknown angle measure at vertex point A.


The distance formula used correctly should give {{{system(AB=2sqrt(5),AC=sqrt(85),BC=5)}}}, that work not shown here.


Law Of Cosines Equation for the described triangle:
{{{AB^2+AC^2-2AB*AC*cos(alpha)=BC^2}}}