Question

the point p (-1,2) is rotated to become p (2,1). describe the rotation by degree and direction. (1 point)
90° rotation counterclockwise
270° rotation clockwise
90° rotation clockwise
180° rotation counterclockwise

Explanation:

Step1: Recall rotation rules

For a 90 - degree clockwise rotation, $(x,y)\to(y, - x)$.
For a 90 - degree counter - clockwise rotation, $(x,y)\to(-y,x)$.
For a 180 - degree rotation, $(x,y)\to(-x,-y)$.
For a 270 - degree clockwise rotation, $(x,y)\to(-y,x)$.

Step2: Check the transformation

Given $P(-1,2)$ and $P'(2,1)$. Applying 90 - degree counter - clockwise rotation on $P(-1,2)$ gives $(-2,-1)$; 270 - degree clockwise rotation on $P(-1,2)$ gives $(-2,-1)$; 90 - degree clockwise rotation on $P(-1,2)$ gives $(2,1)$; 180 - degree counter - clockwise rotation on $P(-1,2)$ gives $(1,-2)$.

Answer:

90° rotation clockwise