Which of following is a key element in the proof of the law of cosines

In proving using the law of cosines, you need to consider these two key elements. The first element is a^2 + b^2 - 2abcosC and the second one is cosine^2 theta + sin^2 theta is equal to 1. Law of Cosines is derived from the Pythagorean Theorem

You would need a laid out graph for this but could you provide a picture of just a graph? i can give stepssolve for y.subtract 4xdivide by -1 (opposites)graph slope intercept formcheck each point to see if it’s on the graph