Question 996837: Rotate polygon ABCD 90 degree counterclockwise about the origin.
A(-4,2)
B(1,3)
C(-2,1)
D(-3,-2)
Found 2 solutions by Edwin McCravy, Theo:
Answer by Edwin McCravy(20055)   (Show Source):
You can put this solution on YOUR website!
Rules for rotating points about the origin
1. The point (a,b) rotated 90° counterclockwise about
the origin becomes (-b,a).
2. The point (a,b) rotated 180° counterclockwise about
the origin becomes (-a,-a).
3. The point (a,b) rotated 270° counterclockwise (or
90° clockwise) about the origin becomes (b,-a).
We use rule 1:
A(-4,2) becomes A'(-2,-4)
B(1,3) becomes B'(-3,1)
C(-2,1) becomes C'(-1,-2)
D(-3,-2) becomes D'(2,-3)
The green polygon below rotated 90° counterclockwise
about the origin becomes the red polygon:
Edwin
Answer by Theo(13342)  (Show Source):
You can put this solution on YOUR website! here's a reference on rotations.
http://www.regentsprep.org/regents/math/geometry/gt4/Rotate.htm
basically, a rotation of 90 degrees counterclockwise results in (x,y) becoming (-y,x).
(-4,2) becomes (-2,-4)
(1,3) becomes (-3,1)
(-2,1) becomes (-1,-2)
(-3,-2) becomes (2,-3)
if you look at each of those points individually, and extend a line from each point to the origin, you will see that they form a 90 degree angle.
here's what the original and the transformed point A looks like.
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