Triangle RST is rotated 90° counterclockwise about the origin. The result is triangle R^ prime S^ prime T^ * ', as shown below.

a.
From the given figure, showing ΔRST and the image ΔR'S'T', the coordinates after the rotation from the original coordinates are:
[tex]\begin{gathered} R(-5,3)\to R^{\prime}(-3,-5) \\ S(-1,1)\to(-1,-1) \\ T(-8,-4)\to(4,-8) \end{gathered}[/tex]b.
The general rule that describes the rotation mapping ΔRST to ΔR'S'T' is:
[tex](x,y)\to(-y,x)[/tex]