3. Rotations
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Let's begin by drawing the segment XY and the line of reflection y=x.
If a point (a,b) is reflected in the line y=x, then its image is the point (b,a).
Point | (a,b) | (b,a) |
---|---|---|
X | (- 3,1) | (1,- 3) |
Y | (4,- 5) | (- 5,4) |
When we know the endpoints of X'Y' we can graph this image.
Next we have to do a rotation of 180^(∘) about the origin. When a figure is rotated 180^(∘) counterclockwise about the origin, the coordinates of the image's endpoints will change in the following way. (a,b)→ (- a,- b) Using this rule on the endpoints of XY, we can find the endpoints of X'Y',
Point | (a,b) | (- a,- b) |
---|---|---|
X' | (1,- 3) | (- 1,3) |
Y' | (- 5,4) | (5,- 4) |
Now we can graph X''Y''.
Finally, we will remove all unnecessary parts of the graph.