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.
Switching x and y reflects the graph over the line y = x (this is equivalent to finding the inverse). Now, x is a function of y . Here are the graphs of y = f (x) and x = f (y) . Note that if (x 1, y 1) is a point on the graph of f (x) and (x 2, y 2) is a point on the graph of f (y) , then y 1 = x 2 and y 2 = x 1 .