Find the equation of a circle with radius 3 units and centre (0, 0). The radius, \(r = 3\) and \(r^2 = 9\), so the equation of the circle is \(x^2 + y^2 = 9\). What is the radius of the circle given ...
Plotting a graph takes time. Often mathematicians just want to know the key features. These are: shape, location and some key points (such as where the graph crosses the axes or turning points).