MA 108 Lecture Notes - Lecture 2: Bisection, Pentagon, Quadrilateral
31 Jan 2019
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Document Summary
Line m is called the line of reflection. A reflection is an isometry, so reflections preserve size (and shape). Reflections reverse the orientation of figures. the plane, we will concentrate on four specific lines of reflection in the coordinate plane: the x- axis, the y-axis, the line y = x, and the line y = x. When a point is reflected in the x-axis, its x-coordinate stays the same, while its y-coordinate changes sign. In coordinate notation, (x", y") = ( x, y ). For example, the point ( 3, 5) has the image (3, -5), and the point ( -2, -7) has the image ( -2, 7). Any point on the x-axis is its own image. If a figure is represented as a polygon matrix, then it can be reflected in the x-axis by multiplying the polygon matrix by the reflection matrix [ 1 0 .
