Suppose a triangle has sides a, b, and c and let theta be the angle opposite the side of length b. If cos (theta)0, what must be true? A) a^2+c^2b^2 B) a^2+b^2=c^2 C) a^2+c^2c^2

Question

Suppose a triangle has sides a, b, and c and let theta be the angle opposite the side of length b. If cos (theta)>0, what must be true? 
A) a^2+c^2>b^2
B) a^2+b^2=c^2
C) a^2+c^2<b^2
D) a^2+b^2>c^2

anonymous · Answer

good question, I need some time.

anonymous · Answer

ok, so have you read the law of cosines, or the vector addition stuff ?

anonymous · Answer

Yes!

anonymous · Answer

good, the law of cosines will give you the answer directly.

anonymous · Answer

try applying it to the triangle, and you'd end up with the solution

anonymous · Answer

so just plug it in?

anonymous · Answer

ya, give it a try

anonymous · Answer

I got it! it was A. thank you so much

anonymous · Answer

sure , the vector addition method is not much different. You can try that too, anyway. Basically, its the same.