Question

One of the endpoints of the base of a triangle is at P(4, 5). The midpoint of the base is at (1, 1). Erik performed the steps shown to find the coordinates of the other endpoint of the base.

Step 1. x1 = 4, y1 = 5, x = 1, y = 1Step 2. Step 3.

Step 4. 2 = 4 + x2, 2 = 5 + y2Step 5. 0 = 4 + x2 , 0 = 5 + y2

Step 6. x2 = -4, y2 = -5In which step did Erik first make an error?