Question

Suppose a triangle has sides a, b, and c let theta be the angle opposite the side of length a. If cos theta < 0 what must be true?

a- b^2+c^2>a^2
b- a^2+b^2=c^2
c- b^2+c^2c^2

Answer 1

cos(theta) being negative means theta is greater than 90 degrees... the triangle is obtuse...
so i think it's c

Answer 2

It was, thanks(:

Answer 3

yw...:)