Explanation:
these 3 points are all on a straight line.
how we can see that without a graph ?
by checking the slope of the connections when going from one point to the next.
from (0, -1) to (2, 1) the changes of x and y are 2 and 2, so the slope is 2/2 = 1.
from (2, 1) to (4, 3) the changes of x and y are again 2 and 2, so the slope is again 2/2 = 1.
so, there is no change in direction from the first 2 points to the third. therefore, they are all on the same straight line, and they are NOT building a right-angled triangle.