Question

In most geometry courses, we learn that there's no such thing as "SSA Congruence". That is, if we have triangles ABC and DEF such that AB=DE, BC=EF, and ∠A=∠D, then we cannot deduce that ABC and DEF are congruent.

However, there are a few special cases in which SSA "works". That is, suppose ABC is a triangle. Let AB=x, BC=y, and ∠A=θ. For some values of x, and θ, we can uniquely determine the third side, AC.

(a) Use the Law of Cosines to derive a quadratic equation in AC.
Can someone please give me a step by step explanation of how to do this? This is due tomorrow! Thanks!!!!