Answer:
A = 62.35°
A = 62° (Appropriately)
Explanation:
To solve for the value of angle A, we employ the COSINE FORMULA.
cos A = (b² + c² - a²) / 2bc
cos B = (a² + c² - b²) / 2ac
cos C = (a² + b² - c²) / 2ab
Where:
A,B,C are the angles of the triangle.
a,b,c are the lengths of the sides
a= 20
b= 16
c= 21
Cos A = (16² + 21² - 20²) / 2*20*16
Cos A = (256 + 441 - 400) / 640
Cos A = 297 / 640
Cos A = 0.464
A = 62.35
A = 62 Appropriately.