Use the law of Cosines to solve the given triangle.Round your answer to two decimal places.
A = 140°,b = 8,c = 9

A)a ≈ 15.98,B ≈ 21.23°,C ≈ 18.77°
B)a ≈ 8,B ≈ 18.77°,C ≈ 21.23°
C)a ≈ 15.98,B ≈ 18.77°,C ≈ 21.23°
D)a ≈ 15.98,B ≈ 20°,C ≈ 20°
E)a ≈ 9,B ≈ 18.77°,C ≈ 21.23°

Question

Use the law of Cosines to solve the given triangle.Round your answer to two decimal places. ​
A = 140°,b = 8,c = 9
​
A)a ≈ 15.98,B ≈ 21.23°,C ≈ 18.77°
B)a ≈ 8,B ≈ 18.77°,C ≈ 21.23°
C)a ≈ 15.98,B ≈ 18.77°,C ≈ 21.23°
D)a ≈ 15.98,B ≈ 20°,C ≈ 20°
E)a ≈ 9,B ≈ 18.77°,C ≈ 21.23°

Quizplus · Accepted Answer

Using the law of cosines:
a^2 = b^2 + c^2 - 2bc*cos(A)
a^2 = 8^2 + 9^2 - 2(8)(9)*cos(140°)
a ≈ 15.98 
Then, we can use the law of sines to find the measures of angles B and C:
sin(B)/b = sin(A)/a 
sin(B)/8 = sin(140°)/15.98 
B ≈ 18.77°
sin(C)/c = sin(A)/a 
sin(C)/9 = sin(140°)/15.98 
C ≈ 21.23°
Therefore, the correct choice is C.

Use the Law of Cosines to Solve the Given Triangle