![]() ![]() So from 0 degrees you take (x, y) and make them negative (-x, -y) and then you've made a 180 degree rotation. A 90 degree turn is 1/4 of the way around a full circle. ![]() We can think of a 60 degree turn as 1/3 of a 180 degree turn. When you rotate by 180 degrees, you take your original x and y, and make them negative. Positive rotation angles mean we turn counterclockwise. If you have a point on (2, 1) and rotate it by 180 degrees, it will end up at (-2, -1) We do the same thing, except X becomes a negative instead of Y. If you understand everything so far, then rotating by -90 degrees should be no issue for you. Our point is as (-2, -1) so when we rotate it 90 degrees, it will be at (1, -2)Īnother 90 degrees will bring us back where we started. A great math tool that we use to show rotations is the coordinate grid. A rotation is an isometric transformation that turns every point of a figure through a specified angle and direction about a fixed point. Longueur dun segment de droite dont les extrémités sont sur une droite graduée. Here is a figure rotated 90° clockwise and counterclockwise about a center point. Droites, demi-droites et segments de droite. These are rigid transformations wherein the image is congruent to its pre-image. Droites, segments de droites et demi-droites. From the definition of the transformation, we have a rotation about any point, reflection over any line, and translation along any vector. What about 90 degrees again? Same thing! But remember that a negative and a negative gives a positive so when we swap X and Y, and make Y negative, Y actually becomes positive. Termes et notations de base en géométrie. ![]() Our point is at (-1, 2) so when we rotate it 90 degrees, it will be at (-2, -1) What if we rotate another 90 degrees? Same thing. Rotation transformation is one of the four types of transformations in geometry. So from 0 degrees you take (x, y), swap them, and make y negative (-y, x) and then you have made a 90 degree rotation. When you rotate by 90 degrees, you take your original X and Y, swap them, and make Y negative. You can use the following rules when performing any clockwise rotation. If you have a point on (2, 1) and rotate it by 90 degrees, it will end up at (-1, 2) A positive degree rotation runs counter clockwise and a negative degree rotation runs clockwise. In case the algebraic method can help you: What are Rotations Rotations are a type of transformation in geometry where we take a point, line, or shape and rotate it clockwise or counterclockwise, usually by 90,180, 270, -90, -180, or -270. ![]()
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