6 9 D 12 15 18 21 Question 4 1 point To use the Cosine Law to solve for an unknown angle you must know a two sides and the angle opposite one of the sides b two angles and the side contained between the two angles c two sides and the angle contained between the two sides d all three sides e none of the above Question 5 1 point The vertex of the parabola defined by the equation y 5 x 2 4 is a 5 4 Ob 2 4 c 2 4 d 5 2 e none of the above Question 6 1 point The count