The cosine rule can be use when you are given three sides of a triangle and ask to find any angle or when you are given two sides and a included angles(the angle between the two sides given) and ask to find the length of a side.
The equation Sophia can use to solve for the side length(b) of a triangle when given two length and the included angle can be expressed below. Sophia was given two sides and an included angle and was asked to find a side length b.
For sides a, b and c the cosine rule can be represented below
I am pretty sure its B (minimum at -1, -4) because that would be were the first point would be at. The Graphing of this equation would be a "upside down u" shape.
