Question

Two vertices of a right triangle have coordinates (9, 1) and (6, −1) .

Select each ordered pair that could be the coordinates of the third vertex.

​​ ​ (9, −1) ​

​ (6, 1) ​

​ ​ (1, −1) ​ ​

​ (6, 9) ​

Answer 1

A & B I think hope this helps! :) 

Answer 2

The points (9, -1) and (6, 1) could form a right triangle with (9,1) and (6, -1).
If you plot the points on graph paper you will see that from (6, -1) to (6, 1)is a vertical line and from (6, 1) to (9, 1) Is a horizontal line. These form right angles.
The same is true for the other pair of points.