Question

If quadrilateral ABCD rotates 90° counterclockwise about the origin, what are the coordinates of A′ in quadrilateral A′B′C′D′ ?

(2, 1)



(-2, -1)



(-2, -2)



(-2, 0)

Answer 1

I believe the answer is (-2,-1) after the original point (2,1) goes through the change of -y,x

Answer 2

Option B is correct.

The coordinate of A' is (-2 , -1)

Step-by-step explanation:

The coordinates of ABCD are A = (-1,2) , B(1,1) , C =(1,-1) and D(-2,-2).

Rotation means moving the shape around a fixed point clockwise or anticlockwise, and by a certain number of degrees.

Rule for 90° counterclockwise rotation about the origin:
`(x,y) \rightarrow (-y,x)`

or we can say that switch x and y in the coordinates and make y value opposite.

Then, the coordinate of A' :

`A(-1,2) \rightarrow A'(-2 ,-1)`

Therefore, the coordinate of A' in the quadrilateral A'B'C'D' is, (-2 ,-1)