A triangle has sides of length (x−1) and (x+2), and angles θ and 2θ, as shown in the diagram.
A triangle ABC is shown. The side AB is labeled x+2, the side AC is labeled x−1, and the side BC is the base. The angle at vertex B is labeled θ, and the angle at vertex C is labeled 2θ.
Show that x=4−3sec2(2θ)4 .