Answer:
d
Step-by-step explanation:
Using the Cosine rule to find ∠ A
cosA = [tex]\frac{b^2+c^2-a^2}{2bc}[/tex]
= [tex]\frac{5.1^2+5.7^2-7.3^2}{2(5.1)(5.7)}[/tex]
= [tex]\frac{26.01+32.49-53.29}{58.14}[/tex]
= [tex]\frac{5.21}{58.14}[/tex] , then
∠ A = [tex]cos^{-1}[/tex] ( [tex]\frac{5.21}{58.14}[/tex] ) ≈ 84.9° ( to 1 dec. place )
