Open Middle®
Directions: Using the digits 1 to 9, at most one time each, place a digit in each box so that the lines through each pair of points are perpendicular.
Hint
What does it mean for lines to be perpendicular?
How can you compare pairs of points so that the lines going through the pairs of points are perpendicular?
How can you compare pairs of points so that the lines going through the pairs of points are perpendicular?
Answer
Here are a couple sets of possible answers.
Line 1: (4, 9) and (3, 2)
Line 2: (1, 6) and (8, 5)
Line 1: (4, 9) and (3, 2)
Line 2: (1, 6) and (8, 5)
Line M: (2, 4) and (8, 6)
Line N: (3, 7) and (5, 1)
Source: Nanette Johnson