Hi I'm reviewing the following solution in my trigonometry text book and I can't figure out how they got their answer. If someone can help explain how they calculated 542.25 for a^2 (nothing I do comes up with that number):

Question

Hi I'm reviewing the following solution in my trigonometry text book and I can't figure out how they got their answer.  If someone can help explain how they calculated 542.25 for a^2 (nothing I do comes up with that number):

a2=b2+c2-2bcCosA
a2=(16)^2+(11)^2 -2(16)(11)Cos118
a2=542.25
|a2=|542.25
a=23.3

Thank you!

Reiny · Answer

I got exactly that. a^2= 16^2 + 11^2 - 2(16)(11)cos118° = 256 + 121 - 352(-.469471562) = 377 + 165.2539898 = 542.253989 a = √542.2539898 = 23.2863 Are you following the order of operation?

Amy · Answer

Thank you, I think it was how I was using my calculator. I didn't add brackets, now I got the same too. Very helpful to have that extra confirmation, I can't tell you how long I've been stuck on this question. Thanks a million!