Rotations

Say I have a square with the points (2,4)-(3,4)-(3,5)-(2,5).

Say I want to rotate this square 90 degrees around the origin I get the points
(-4,2)-(-5,2)-(-5,3)-(-4,3) I did this by spinning my paper 90 degrees. How can I use a protractor to be able to solve this problem? This is the way that I am suppose to solve this problem by using a protractor and I really do not understand how to do this. Thank you for any help. Or do you know how I can solve this besides turning my paper the alloted degrees and getting the coordinates.

Quote:

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Originally Posted by schinb64

Say I have a square with the points (2,4)-(3,4)-(3,5)-(2,5).

Say I want to rotate this square 90 degrees around the origin. ... Or do you know how I can solve this besides turning my paper the alloted degrees and getting the coordinates.

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I've attached adrawing to show you how this construction can be done:

1. The concentric circles are the paths on which the vertices of the square are moving during the rotation.

2. Construct a line perpendicular to OA.

3. Where this line intersect the circle passing through A the image of A, A', is located.

4. Do the same procedure for the last 3 vertices.

5. Connect all points A', B', C' and D'. Check if you actually got a square.