Suppose you rotate triangle ABC counterclockwise 90º. If ABC has vertices A (-2, 1), B (-1, 4), and C (2, 2), vertex A' is (-1, ?).

Question

abbles · Answer

I assume you mean rotating the triangle about the origin.  If so, the rule to do that is (-y, x).

anonymous · Answer

How do you apply that rule?

abbles · Answer

So the original coordinates of A are (-2, 1) which is in the form (x, y).  -2 is the x and 1 is the y.  Now plug those into (-y, x)

anonymous · Answer

That would give me (2, 1), but the question itself says that the X point of the rotated vertices is -1?

abbles · Answer

Actually it would give you (-1, -2) because 1 is the y value and it needs to be negated and then put before the x value, -2.

anonymous · Answer

Oh shoot! I see where I went wrong with your instructions, thank you I understand!

abbles · Answer

Okay :) glad I could help