Question

rotate point a 90° counter - clockwise about the origin. enter the new coordinates. a = (?, )

Explanation:

Step1: Recall rotation rule

The rule for rotating a point $(x,y)$ 90 - degrees counter - clockwise about the origin is $(x,y)\to(-y,x)$.

Step2: Apply the rule

Given point A with coordinates $(1,3)$. Here $x = 1$ and $y = 3$. Using the rule, we get $x'=-y=-3$ and $y'=x = 1$.

Answer:

$A'=(-3,1)$