Need understanding !

micheal is constructing a circle circumscribed about a triangle. he has partially completed the construction, as shown below. what should be his next step? (picture attached with wrong answer)

Select the correct answer from each drop-down menu. a system of equations and its solution are given below. system a complete the sentences to explain what steps were followed to obtain the system of equations below. system b to get system b, the equation in system a was replaced by the sum of that equation and times the equation. the solution to system b the same as the solution to system a.]