jman15 said:
i get to c^2=25 cos C Nope.
It looks like you're using C for theta, right? That's okay.
And, the value of c is 8, so I'm not sure why you're typing c^2 instead of 8^2.
On these boards, you'll find that time is saved, if you show your work. Without seeing it, I can't tell where you went wrong.
When we use the Law of Cosines with an angle theta, then the triangle side opposite angle theta is always the side^2 that appears in the formula all by itself on one side of the equals sign.
\(\displaystyle a^2 \;=\; b^2 \;+\; c^2 \;-\; 2 \ b \ c \ cos(\theta)\)
? Use this form when side a is opposite theta.
\(\displaystyle b^2 \;=\; a^2 \;+\; c^2 \;-\; 2 \ a \ c \ cos(\theta)\)
? Use this form when side b is opposite theta.
\(\displaystyle c^2 \;=\; a^2 \;+\; b^2 \;-\; 2 \ a \ b \ cos(\theta)\)
? Use this form when side c is opposite theta.
Try the Law of Cosines again, plugging the values a = 14, b = 19, and c = 8 into the third form listed above because side c is opposite theta, in this exercise.
If you cannot simplify to cos(C) = 493/532, please show your work.
Cheers ~ Mark
