SOLUTION: c^2=13^2+20^2-2(13)(20)cos27 This is where I don't understand. I know the answer is c^2=105.68, but when I work it out I get 720.9121805, which is nowhere the correct answer. I

Algebra ->  Trigonometry-basics -> SOLUTION: c^2=13^2+20^2-2(13)(20)cos27 This is where I don't understand. I know the answer is c^2=105.68, but when I work it out I get 720.9121805, which is nowhere the correct answer. I       Log On


   

Question 185376This question is from textbook saxon algebra 2
: c^2=13^2+20^2-2(13)(20)cos27
This is where I don't understand. I know the answer is c^2=105.68, but when I work it out I get 720.9121805, which is nowhere the correct answer. I am working it straight across. What am I doing wrong? Please help! This question is from textbook saxon algebra 2

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
It's possible that you are working in radian mode where you actually want to work in degree mode.


c%5E2=13%5E2%2B20%5E2-2%2813%29%2820%29cos%2827%29 Start with the given equation.


c%5E2=169%2B400-2%2813%29%2820%29cos%2827%29 Square each term.


c%5E2=169%2B400-2%2813%29%2820%29%280.891%29 Evaluate the cosine of 27 to get 0.891 (if you get a different value, then you're in the wrong mode).


c%5E2=169%2B400-463.32 Multiply


c%5E2=105.68 Combine like terms.


So you're answer is confirmed to be c%5E2=105.68