Step 1 :The problem is asking to rotate a triangle 90 degrees counterclockwise about the origin. The transformation rule for a 90 degree counterclockwise rotation about the origin is \((x, y) \rightarrow (-y, x)\). This means that for each point \((x, y)\) in the triangle, we replace x with -y and y with x to get the new coordinates of the point after rotation.
Step 2 :Let's apply this rule to the vertices of the triangle \(PQR\) with coordinates \((1, 2)\), \((3, 4)\), and \((5, 6)\).
Step 3 :For point P \((1, 2)\), replacing x with -y and y with x gives us \((-2, 1)\).
Step 4 :For point Q \((3, 4)\), replacing x with -y and y with x gives us \((-4, 3)\).
Step 5 :For point R \((5, 6)\), replacing x with -y and y with x gives us \((-6, 5)\).
Step 6 :Thus, the image of the triangle \(PQR\) under a \(90^\circ\) rotation about the origin is the triangle with vertices at \((-2, 1)\), \((-4, 3)\), and \((-6, 5)\).
Step 7 :In other words, \(\triangle PQR\) is transformed to \(\triangle P'Q'R'\) where \(P' = (-2, 1)\), \(Q' = (-4, 3)\), and \(R' = (-6, 5)\).
Step 8 :\(\boxed{\text{Final Answer: } P' = (-2, 1), Q' = (-4, 3), R' = (-6, 5)}\)