Answer: A. 31.5
Step-by-step explanation:
Using law of cosine because it is side angle side
a=16
b=21
angle = 116
c^2=a^2+b^2-2ab cosC, let C be the angle given
c^2=(21)^2+(16)^2-2(16)(21) cos(116)
c^2=441+256-672 cos(116)
i used a ti-89 and answered the right side and got
(you can find a ti-89 simulator online, but for problems like this make sure it is in degree mode)
991.585
c^2=991.585
take square root of both sides
=31.4894, which if you round it up it would be 31.5, so the answer would be A
therefore:
a=16
b=21
c=31.5
