A graph of a linear function f(x) = kx+b is a line. There are various types of its construction (use radio buttons to select one). First, by 2 points. Define two points of the line by clicking twice on the coordinate system. Solve an equation set y_{1}=kx_{1}+b and y_{2}=kx_{2}+b where (x_{1}, y_{1}) and (x_{2}, y_{2}) the coordinates of plotted points for variables k and b. Draw a line through the points. Second, by points of intersection with axes. Define a point by clicking on axis X and another on axis Y. Then a line through the points is draw. This type is similar to the previous one. Third, by a point and an angle between the line and axis X. Define a point by mouse click and an angle by mouse motion. A line is drawn. The coefficient k is a tangent of the angle.
