Posted by Amy on .
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+c22bcCosA
a2=(16)^2+(11)^2 2(16)(11)Cos118
a2=542.25
a2=542.25
a=23.3
Thank you!

Math 
Reiny,
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? 
Math 
Amy,
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!