Answer:
15√3/14.
Step-by-step explanation:
C. The longest side x + 2 = 7 is opposite the largest angle 120 degrees. The other 2 sides are of length 3 and 5.
Using the Sine Law:
sin 120 = √3/ 2 = sin A'
7 / sin 120 = 5/ sin B
sin B = 5 sin 120 / 7 = 5√3/14.
7 / sin 120 = 3 / sin C
sin C = 3 sin 120 / 7 = 3√3 / 14
sin A + sin B + sin C = √3/ 2 + 5√3/14 + 3√3 / 14
= 7√3/ 14 + 5√3/14 + 3√3 / 14
= 15√3/14.
