The solutions for the triangle are: ∠A = 51.833...° , ∠B = 70.880...° and ∠C = 57.286...°
Explanation
For finding the unknown angles, we need to use Cosine rule. The formulas are...
[tex]cos A = \frac{b^2+c^2-a^2}{2bc} \\ \\ cos B= \frac{a^2+c^2-b^2}{2ac}\\ \\ cos C= \frac{a^2+b^2-c^2}{2ab}[/tex]
Given that the length of three sides of the triangle as : [tex]a= 11.4, b= 13.7[/tex] and [tex]c=12.2[/tex]
Thus,
[tex]cosA= \frac{(13.7)^2+(12.2)^2 -(11.4)^2}{2(13.7)(12.2)} \\ \\ cosA= \frac{206.57}{334.28} \\ \\ cosA= 0.61795... \\ \\ A= cos^-^1 (0.61795...)= 51.833... degree\\ \\ \\ \\ cos B= \frac{(11.4)^2+(12.2)^2 -(13.7)^2}{2(11.4)(12.2)}\\ \\ cos B= \frac{91.11}{278.16} \\ \\ cos B= 0.3275...\\ \\ B= cos^-^1 (0.3275...)= 70.880... degree \\ \\ \\ \\ cos C= \frac{(11.4)^2+(13.7)^2 -(12.2)^2}{2(11.4)(13.7)}\\ \\ cos C= \frac{168.81}{312.36} \\ \\ cos C= 0.54043...\\ \\ C= cos^-^1 (0.54043...)= 57.286... degree[/tex]
Answer
To simplify the answer above this one, it is
C) A=51.8 B=70.9 C=57.3
Step-by-step explanation:
I got it right on edge
