Find all points on the y-axis that are 5 units from the point (4,4). Points on the y-axis have the form (0,y) Solve the distance equation: 5 = sqrt[(4-0)^2 + (4-y)^2] 25 = 16 + 16 - 8y + y^2 y^2 - 8y + 7 = 0 (y-7)(y-1) = 0 y = 7 or y = 1 Points: (0,7) and (0,1) The midpoint of the line segment from P1 to P2 is (5,-4). if P2 is (7,-2), what is P1? Let P1 be (x,y) Note: The coordinates of the midpoint are the average of the corresponding endpoint coordinate (x+7)/2 = 5 x+7 = 10 x = 3 (y-2)/2 = -4 y-2 = -8 y = -6 P1 is (3,-6)