Instruction Active
Writing a Rule for a Rotation
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What rule describes the rotation about the origin?
C'
(x, y)
4
tated about the
✓
2
A'
B'
(y, -x)
-4
-2
2
(-y, x)
B
A
-2
(-x-y)
(x, y)

Explanation:

Focus on one point, such as A = (1,2). Note how it moves to point A ' = (-1, -2). Both x and y coordinates have been flipped from positive to negative. The rule therefore is . This describes a 180 degree rotation (either clockwise or counterclockwise, it doesn't matter). Points B and C follow the same idea.

Side note: Lines AA', BB' and CC' all go through the origin (0,0).

step-by-step explanation:

step 1: solve one of the equations for one of the variables. let's solve the first equation for y:

step 2: substitute that equation into the other equation, and solve for x.

step 3: substitute x = 4 x = 4 x=4 into one of the original equations, and solve for y.