Question

suppose a triangle has sides a,b and c and that a^2+b^2 < c^2 . Let theta be the measure of the angle opposite the side of length c. Which of the following must be true? check all that apply


A) cos (theta)> 0

B) the triangle is not a right triangle

C)a^2+b^2-c^2 = 2abcos(theta)

D) cos (theta) < 0