Question 550783
A triangle is made up of three points that aren't all on the same line.


{{{drawing( 300, 300, -10, 10, -10, 10,
  grid(1),
  circle( 1, 3, .2 ),
  circle( 4, 0, .2 ),
  circle( 10, -6, .2 )
)}}}

Looking at our three points we can see they are on a line. We can also determine that they are on a line by finding the equation of the lines or just by looking that all three points are along the same slope. From R to S our slope is 3/-3 and if we continue to add three to our y and subtract 3 to our x we get (7,-3) and then 10,-6 so we are along a line.

If you need a different kind of way to determine this, please specify.