51722210
Points \(A(2, 2)\), \(B(10, 2)\), and \(C(10, 8)\) are given.
a) Find the coordinates of point \(D\) so that \(A\), \(B\), \(C\), and \(D\), in that order, form a rectangle.
b) Point \(M\) is the midpoint of \(\overline{AB}\). Find the coordinates of \(M\).
Hints
- In an axis-aligned rectangle, which coordinates are shared by vertically or horizontally aligned vertices?
- The midpoint coordinates are the averages of the corresponding endpoint coordinates.
- Check the x-coordinates and y-coordinates separately.
Solution
1. In rectangle \(ABCD\), point \(D\) must have the same x-coordinate as \(A\) and the same y-coordinate as \(C\). Therefore, \(D = (2, 8)\).
2. Use the midpoint formula on \(A(2, 2)\) and \(B(10, 2)\): \(M = \left(\frac{2 + 10}{2}, \frac{2 + 2}{2}\right) = (6, 2)\).
Answer
a) \(D = (2, 8)\)
b) \(M = (6, 2)\)
