Answer:
Explanation:
Use law of Cos to solve for angle
Law of Cos:
c² = a² + b² - 2ab cos C
20² = 23² + 19² - 2(23)(19) cos C
400 = 529 + 361 - 874 cos C
400 = 890 - 874 cos C
-490 = -874 cos C
cos C = .5606
C = cos⁻¹ .5606
C = 55.90
Use again to find angle B
b² = a² + c² - 2ac cos B
19² = 23² + 20² - 2(23)(20) cos B
361 = 529 + 400 - 920 cos B
361 = 929 - 920 cos B
-568 = -920 cos B
cos B = .6174
B = cos⁻¹ .6174
B = 51.87
A = 180 - B - C
A= 180 - 51.87 - 55.90
A= 72.23