Question

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

Please explain. Thank you!

Answer 1

if cos theta < 0, then it is negative.


cos(theta) = adjacent side/hypotenuse.

If cosine is negative, then it's not in quadrant 4.

Answer 2

as for what is true, I can't help you with that sorry. Either side a, c, or both are negative. side c is always the largest side, however.

Answer 3

If c is the hypotenuse,

Answer 4

*sorry, either sides b or c are negative

Answer 5

*or both

Answer 6

Law of Cosines