Question

The midpoint of sm is (5,-11). One endpoint is S(3,5). What are the coordinates of endpoint M?

Answer 1

The coordinates of the midpoint if the endpoints are (x₁,y₁) and (x₂,y₂):
$(\frac{x_1+x_2}{2}, \frac{y_1+y_2}{2})$

One endpoint is (3,5), the midpoint is (5,-11). The other endpoint is (x,y).

$\frac{3+x}{2}=5 \ \ \ \ \ \ \ \ |\times 2 \\ 3+x=10 \ \ \ \ \ |-3 \\ x=7 \\ \\ \frac{5+y}{2}=-11 \ \ \ \ \ |\times 2 \\ 5+y=-22 \ \ \ |-5 \\ y=-27$

The coordinates of endpoint M are (7,-27).