The fourth corner, then a reflection
Finding a missing coordinate to complete a rectangle, then reflecting a point in the y-axis.
The Question
A is (1, 2), B is (7, 2) and C is (7, 6). Give the coordinates of D so that ABCD is a rectangle. Then reflect D in the y-axis and give its new coordinates.
The Answer
Reveal the Answer
AB is horizontal and BC is vertical, so D sits above A: same x as A, same y as C, giving (1, 6). Reflecting in the y-axis flips the sign of x only, so (1, 6) becomes (−1, 6). Sketch it — the fourth corner is obvious on paper and easy to get wrong in your head.
Now watch the solution
Practice Sheet + Marked Answers
The four-question practice sheet, the solutions in our teaching voice and a self-marking quiz for this question are part of The Question Desk course — every school day of the term, with progress you can see. Enrolled group students get it included.
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