Question

The midpoint of start overline, AB, end overline
AB
is M, left parenthesis, 2, comma, 1, right parenthesisM(2,1). If the coordinates of AA are left parenthesis, minus, 3, comma, minus, 1, right parenthesis(−3,−1), what are the coordinates of BB?

Answer 1

Use the midpoint formula: M = ((x_A + x_B)/2, (y_A + y_B)/2).

So
2 = (−3 + x_B)/2 → x_B = 2·2 − (−3) = 4 + 3 = 7
1 = (−1 + y_B)/2 → y_B = 2·1 − (−1) = 2 + 1 = 3

Thus B = (7, 3).