極座標: 問題解決

Engineers often model the coverage area of a radio tower using polar curves to describe its directional broadcast pattern.

A common model for these curves is the four-lobed rose curve. Here, r represents the maximum distance the signal reaches at a given angle theta.

Each lobe of this curve represents a focused directional beam. To ensure proper network planning, the geographic area covered by a single beam must be calculated.

This area is found by integrating one-half the square of the radius, which is the universal method for calculating the area of a region in polar coordinates.

Here, a single lobe begins and ends at the origin, where r = 0. Substituting the value of r and solving gives two values of theta: -pi/4 and pi/4.

Substituting the equation and limits into the area formula gives an integral involving the cosine squared of two theta.

By applying the trigonometric reduction identity and evaluating the integral over the given limits, the area is found.

This area provides the geographic coverage of a single signal beam, aiding in planning the placement of surrounding towers.