A graph of function f(x) = ax^{2}+bx+c if a is not equal to zero is called a parabola. A trajectory of a missile is an example of a parabola. Consider a missile start from the point of origin with velocity V and an angle of departure α. The horizontal and vertical part of motion for the missile is described by set of equations x(t) = t∙V cos α and y(t) = t∙V sin α  g t^{2}. Thus y(x) = x∙tg α + x^{2}∙g/(V^{2} cos^{2} α). This is a quadratic function with a = g/(V^{2} cos^{2} α), b = tg α and c = 0. Cross points of its graph with axis OX are the point of origin and a point (0; L) where L = (V^{2}∙sin 2α) / g is a shot distance. The model has 2 modes: a Demonstration and a Find distance. In Demonstration mode you can set the initial speed and the angle. Corresponding shot distance calculates automatically. The Start button draw a graph of the given function (the missile trajectory) and allows you to observe the missile flying. A Next button allow you to set a different initial data. In Find distance mode you should find a shot distance for given values of V and α. Enter the solution to place the refuse bin correctly. Press the Check button to observe shooting. Press the Show solution button to see a correct solution.
