Answer:



Step-by-step explanation:
Given



Required
The measure of each angle
First, we calculate the length of the three sides of the triangle.
This is calculated using distance formula

For AB





So:

For BC





For AC





So, we have:



By representation



So, we have:



By cosine laws, the angles are calculated using:







Collect like terms


Solve for 


Take arc cos of both sides





Collect like terms


Solve for 


Take arc cos of both sides


For the third angle, we use:
--- angles in a triangle
Make C the subject



5 - 6 = -1
2 + 7 = 9
-1 × 9 = -9
-9 would be the simplified answer.
Hope this helps!