A) if c is the line segment connecting the point (x1, y1) to the point (x2, y2), find the following. x dy − y dx c correct: your answer is correct. (b) if the vertices of a polygon, in counterclockwise order, are (x1, y1), (x2, y2), , (xn, yn), find the area of the polygon. a = 1 2 (x1y2 − x2y1) − (x2y3 − x3y2) − − (xn − 1yn − xn n − 1) + (xny 1 − x1yn) a = 1 2 (x1y2 + x2y1) + (x2y3 + x3y2) + + (xn − 1yn + xn n − 1) + (xny 1 + x 1 yn) a = 1 2 (x2y1 − x1y2) + (x3y2 − x2y3) + + (xnyn−1 − xn−1yn) + (x1yn − xny1) a = (x1y2 − x2y1) + (x2y3 − x3y2) + + (xn − 1yn − xnyn − 1) + (xny1 − x1yn) a = 1 2 (x1y2 − x2y1) + (x2y3 − x3y2) + + (xn − 1yn − xnyn − 1) + (xny1 − x1yn) correct: your answer is correct. (c) find the area of the pentagon with vertices (0, 0), (4, 1), (1, 3), (0, 1), and (−2, 1).