![rule for 90 degree rotation geometry rule for 90 degree rotation geometry](https://cdn.virtualnerd.com/thumbnails/PreAlg_09_01_0032-diagram_thumb-lg.png)
That and it looks like it is getting us right to point A. Our center of rotation, this is our point P, and we're rotating by negative 90 degrees. Which point is the image of P? So once again, pause this video and try to think about it. In other words, switch x and y and make y negative. Rotating a polygon clockwise 90 degrees around the origin. Than 60 degree rotation, so I won't go with that one. The most common rotations are 180 or 90 turns, and occasionally, 270 turns, about the origin, and affect each point of a figure as follows: Rotations About The Origin 90 Degree Rotation When rotating a point 90 degrees counterclockwise about the origin our point A (x,y) becomes A' (-y,x). For rotating 90 degrees counterclockwise about the origin, a point (x, y) becomes (-y, x). And it looks like it's the same distance from the origin. Great question There are actually several helpful shortcuts for finding rotations. Like 1/3 of 180 degrees, 60 degrees, it gets us to point C. So does this look like 1/3 of 180 degrees? Remember, 180 degrees wouldīe almost a full line. One way to think about 60 degrees, is that that's 1/3 of 180 degrees. So this looks like aboutĦ0 degrees right over here. P is right over here and we're rotating by positive 60 degrees, so that means we go counterĬlockwise by 60 degrees. It's being rotated around the origin (0,0) by 60 degrees. Which point is the image of P? Pause this video and see
![rule for 90 degree rotation geometry rule for 90 degree rotation geometry](https://us-static.z-dn.net/files/d48/80f4673512aff8bfb9b1b289800c7fcf.png)
That point P was rotated about the origin (0,0) by 60 degrees. Note that a geometry rotation does not result in a change or size and is not the same as a reflection Clockwise vs. I included some other materials so you can also check it out. There are many different explains, but above is what I searched for and I believe should be the answer to your question. There is also a system where positive degree is clockwise and negative degree anti-clockwise, but it isn't widely used. Product of unit vector in X direction with that in the Y direction has to be the unit vector in the Z direction (coming towards us from the origin). Clockwise for negative degree.įor your second question, it is mainly a conventional that mathematicians determined a long time ago for easier calculation in various aspects such as vectors.