Question

1. reflection across y = x

Explanation:

Step1: Recall reflection rule

The rule for reflecting a point $(x,y)$ across the line $y = x$ is $(x,y)\to(y,x)$.

Step2: Identify original points

Assume the coordinates of $S$ are $(x_1,y_1)$, $T$ are $(x_2,y_2)$ and $U$ are $(x_3,y_3)$. From the graph, if we assume $S=(1, - 3)$, $T=(3,1)$ and $U=(3,-3)$.

Step3: Apply reflection rule

For point $S(1,-3)$, after reflection across $y = x$, $S'=(-3,1)$.
For point $T(3,1)$, after reflection across $y = x$, $T'=(1,3)$.
For point $U(3,-3)$, after reflection across $y = x$, $U'=(-3,3)$.

Answer:

$S'(-3,1)$
$T'(1,3)$
$U'(-3,3)$