This means that the (x,y) coordinates will be completely unchanged! We don't really need to cover a rotation of 360 degrees since this will bring us right back to our starting point. When rotating a point around the origin by 270 degrees, (x,y) becomes (y,-x). Now let's consider a 270-degree rotation:Ĭan you spot the pattern? The general rule here is as follows: When we rotate a point around the origin by 180 degrees, the rule is as follows: We can see another predictable pattern here. Now let's consider a 180-degree rotation: With a 90-degree rotation around the origin, (x,y) becomes (-y,x) We might have noticed a pattern: The values are reversed, with the y value on the rotated point becoming negative. Let's start with everyone's favorite: The right, 90-degree angle:Īs we can see, we have transformed P by rotating it 90 degrees. Some of the most useful rules to memorize are the transformations of common angles. There are many important rules when it comes to rotation. On the other hand, we can also use certain calculations to determine the amount of rotation even without graphing our points. We measure the "amount" of rotation in degrees, and we can do this manually using a protractor. Just like the wheel on a bicycle, a figure on a graph rotates around its axis or " center of rotation." As it turns out, the mathematical definition of rotation isn't all that different. We can even rotate ourselves by spinning around until we get dizzy. After all, the wheels on a bicycle or a skateboard rotate. We're probably already familiar with the concept of rotation. But how exactly does this work? Let's find out: What is a rotation? One of these techniques is "rotation." As we might have guessed, this involves turning a figure around on its axis. You can know how to slide a shape using the T ( a, b ) T ( − 10, 3 ) because the first value is always the x-axis.As we get further into geometry, we will learn many different techniques for transforming graphs. To avoid confusion, the new image is indicated with a little prime stroke, like this: P′, and that point is pronounced “ P prime. Suppose you have Point P located at (3, 4). The original reference point for any figure or shape is presented with its coordinates, using the x-axis and y-axis system, (x,y). Reflection – exchanging all points of a shape or figure with their mirror image across a given line (like looking in a mirror) Stretch – a one-way or two-way change using an invariant line and a scale factor (as if the shape were rubber) Shear – a movement of all the shape’s points in one direction except for points on a given line (like a crate being collapsed) Rotation – turning the object around a given fixed pointĭilation – a decrease in scale (like a photocopy shrinkage)Įxpansion – an increase in scale (like a photocopy enlargement) Translation – moving the shape without any other change You can perform seven types of transformations on any shape or figure: Translations are the simplest transformation in geometry and are often the first step in performing other transformations on a figure or shape.įor example, you may find you want to translate and rotate a shape. an isometry) because it does not change the size or shape of the original figure. A translation is a rigid transformation (a.k.a.
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