Question

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

Answer 1

If the coordinates of point B are (a,b),

then the coordinates of point B' are (-b,a).


^ y
B' |
*–––––––-|
\ -b |
\ | B
\ a | |
\ | / |
\ | / b |
\ | / |
\|/________a______|___> x

Answer 2

not sure tho

Answer 3

so wat you think the answer is