![]() And so this would be negative 90 degrees, definitely feel good about that. And this looks like a right angle, definitely more like a rightĪngle than a 60-degree angle. And once again, we are moving clockwise, so it's a negative rotation. This is where D is, and this is where D-prime is. Point and feel good that that also meets that negative 90 degrees. Example 1 : The triangle XYZ has the following vertices X(0, 0), Y(2, 0) and Z(2, 4). This looks like a right angle, so I feel good about We can use the rules shown in the table for changing the signs of the coordinates after a reflection about the origin. We are going clockwise, so it's going to be a negative rotation. Too close to, I'll use black, so we're going from B toī-prime right over here. Let me do a new color here, just 'cause this color is Much did I have to rotate it? I could do B to B-prime, although this might beĪ little bit too close. I can take some initial pointĪnd then look at its image and think about, well, how I don't have a coordinate plane here, but it's the same notion. Well, I'm gonna tackle this the same way. So once again, pause this video, and see if you can figure it out. So we are told quadrilateral A-prime, B-prime, C-prime,ĭ-prime, in red here, is the image of quadrilateralĪBCD, in blue here, under rotation about point Q. So just looking at A toĪ-prime makes me feel good that this was a 60-degree rotation. And if you do that with any of the points, you would see a similar thing. Another way to thinkĪbout is that 60 degrees is 1/3 of 180 degrees, which this also looks Like 2/3 of a right angle, so I'll go with 60 degrees. One, 60 degrees wouldīe 2/3 of a right angle, while 30 degrees wouldīe 1/3 of a right angle. This 30 degrees or 60 degrees? And there's a bunch of ways The counterclockwise direction, so it's going to have a positive angle. And where does it get rotated to? Well, it gets rotated to right over here. Remember we're rotating about the origin. Points have to be rotated to go from A to A-prime, or B to B-prime, or from C to C-prime? So let's just start with A. So I'm just gonna think about how did each of these So like always, pause this video, see if you can figure it out. Common rotation angles are \(90^\) anti-clockwise : (-6.- We're told that triangle A-prime, B-prime, C-prime, so that's this red triangle over here, is the image of triangle ABC, so that's this blue triangle here, under rotation about the origin, so we're rotating about the origin here. Rotation can be done in both directions like clockwise and anti-clockwise. As a convention, we denote the anti-clockwise rotation as a positive angle and clockwise rotation as a negative angle. The amount of rotation is in terms of the angle of rotation and is measured in degrees. The point about which the object is rotating, maybe inside the object or anywhere outside it. ![]() The direction of rotation may be clockwise or anticlockwise. Thus A rotation is a transformation in which the body is rotated about a fixed point. vertex The point at which two or more lines intersect (cross or overlap). In the mathematical term rotation axis in two dimensions is a mapping from the XY-Cartesian point system. centre of rotation A fixed point about which a shape is rotated. The rotation transformation is about turning a figure along with the given point. The point about which the object rotates is the rotation about a point. ![]() The rotations around the X, Y and Z axes are termed as the principal rotations. In three-dimensional shapes, the objects can rotate about an infinite number of imaginary lines known as rotation axis or axis of motion. It is possible to rotate many shapes by the angle around the centre point. Rotation means the circular movement of somebody around a given centre. From other geometry videos and lessons we have learned about similarity and congruency in polygons, particularly triangles. Thus, in Physics, the general laws of motions are also applicable for the rotational motions with their equations. But, many of the equations for the mechanics of the rotating body are similar to the linear motion equations. Rotational motion is more complex in comparison to linear motion. Such motions are also termed as rotational motion. Also, the rotation of the body about the fixed point in the space. The motion of some rigid body which takes place so that all of its particles move in the circles about an axis with a common velocity. This article will give the very fundamental concept about the Rotation and its related terms and rules. In geometry, four basic types of transformations are Rotation, Reflection, Translation, and Resizing. In our real-life, we all know that earth rotates on its own axis, which is a natural rotational motion. It is applicable for the rotational or circular motion of some object around the centre or some axis. The term rotation is common in Maths as well as in science.
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