bilateral symmetry the configuration of an irregularly shaped body (such as the human body or that of higher animals) that can be divided by a longitudinal plane into halves that are mirror images of each other. radial symmetry that in which the body parts are arranged regularly around a central axis.he configuration of an irregularly shaped body (such as the body of a higher animal) that can be divided by a longitudinal plane into halves that are mirror images of each other. radial symmetry. that in which the body parts are arranged regularly around a central axis.
Linear Functions. If the power of both x and y in a relation is one, then the relation is called a linear relation or linear function. For example, y = 3x + 5, 7x  8y = 56 and 2x + 3y + 6 = 0 are linear functions because the power of both x and y is one. Plotting Graphs of Linear Functions.
Linear Functions and Equations. Linear functions are functions that have x as the input variable, and x has an exponent of only 1. Such functions look like the ones in the graphic to the left. Notice that x has an exponent of 1 in each equation. Functions such as these yield graphs that are straight lines, and, thus, the name linear. Linear functions come in three main forms. An explanation and animation are available for each by clicking the links below. A very common way to express a linear function is named the 'slope-intercept form' of a linear function.