Question

One endpoint of a line segment has the coordinates (-5, 12). If the midpoint of the segment is at (2,9), find the

coordinates of the missing endpoint.

Answer 1

(9, 6)

Explanation:

Midpoint formula is:

• x = (x₁ + x₂)/2
• y = (y₁ + y₂)/2

Having coordinates of one end- and midpoint (-5, 12) and (2, 9):

• x₁ = -5, y₁ = 12
• x = 2, y = 9

we get the coordinates of the missing endpoint with coordinates (x₂, y₂):

• x₂ = 2x - x₁ = 2*2 - (-5) = 4 + 5 = 9
• y₂ = 2y - y₁ = 2*9 - 12 = 18 - 12 = 6

So the missing point is: (9, 6)