100 points! Please help! If the total perimeter of the triangle is 5x 3+ 4x 2− x – 3, what is the length of the third side of the triangle? (This will require subtraction) Please show steps

Which statement explains how you could use coordinate geometry to prove the opposite sides of a quadrilateral are congruent? a. use the slope formula to prove the slopes of the opposite sides are the same. b. use the slope formula to prove the slopes of the opposite sides are opposite reciprocals. c. use the distance formula to prove the lengths of the opposite sides are the same. d. use the distance formula to prove the midpoints of the opposite sides are the same.