Answer:
∠ A ≈ 24.1°
Step-by-step explanation:
Using the law of sines , then
[tex]\frac{9}{sinA}[/tex] = [tex]\frac{21}{sin72}[/tex] ( cross- multiply )
21 × sinA = 9 × sin72° ( divide both sides by 21 )
sinA = [tex]\frac{9sin72}{21}[/tex] , then
∠ A = [tex]sin^{-1}[/tex] ( [tex]\frac{9sin72}{21}[/tex] ) ≈ 24.1° ( to the nearest tenth )
