What is an easier way to solve algebraic expressions?

How do you use the elimination method for this question? explain, because i really want to understand!

What is the relationship between all triangles that can be drawn given the same three angles

Graph g(x)=2cosx . use 3.14 for π . use the sine tool to graph the function. graph the function by plotting two points. the first point must be on the midline and closest to the origin. the second point must be a maximum or minimum value on the graph closest to the first point.