The figure shown at the right is a rotation of 90° rotated around the center of rotation. Also, rotations are done counterclockwise! You can rotate your object at any degree measure, but 90° and 180° are two of the most common. Reflection over line y = x: T( x, y) = ( y, x)Ī rotation is a transformation that is performed by 'spinning' the object around a fixed point known as the center of rotation.

Reflection over y-axis: T(x, y) = (- x, y) Reflection over x-axis: T( x, y) = ( x, - y) In other words, the line of reflection is directly in the middle of both points.Įxamples of transformation geometry in the coordinate plane. The line of reflection is equidistant from both red points, blue points, and green points. Notice the colored vertices for each of the triangles. Let's look at two very common reflections: a horizontal reflection and a vertical reflection. The transformation for this example would be T( x, y) = ( x+5, y+3).Ī reflection is a 'flip' of an object over a line. More advanced transformation geometry is done on the coordinate plane. In this case, the rule is '5 to the right and 3 up.' You can also translate a pre-image to the left, down, or any combination of two of the four directions. The formal definition of a translation is 'every point of the pre-image is moved the same distance in the same direction to form the image.' Take a look at the picture below for some clarification.Įach translation follows a rule. The most basic transformation is the translation. Translations - Each Point is Moved the Same Way

The original figure is called the pre-image the new (copied) picture is called the image of the transformation.Ī rigid transformation is one in which the pre-image and the image both have the exact same size and shape.

Rotations geometry rules