### III. Working With Graphs

B. F2 - Zoom

The Zoom menu is a very useful tool when working with graph. The Zoom menu offers you several preset windows and numerous other options. Zoom can be a very powerful tool when analyzing a graph. There are many times when one of these options will work well with the function you are graphing. To access the Zoom menu from the graph window press . To access the Zoom menu from the Window menu, press or .

 From the graph window press .

 1:ZoomBox This allows you to box in a particular area of the graph and then zoom in on that selected portion. 2:ZoomIn You can select a point on the graph and then zoom in or zoom out with that point as the center. The amount of zoom is defined by SetFactors (see below). 3:ZoomOut 4:ZoomDec This is one of the most useful windows. It is also called a friendly window because the Trace key will move in set increments of .1 times the value of xres. The window size is x:[-7.9,7.9] and y:[-3.8, 3.8]. 5:ZoomSqr This adjusts the Window variables so that the ticks on each axis are the same distance apart. This will allow squares and circles to be shown in correct proportions. 6:ZoomStd Sets the Window variables to the default values. x:[-10,10] and y:[-10,10]. 7:ZoomTrig Sets the Window variables to increments using , and are appropriate for many trigonometric functions. 8:ZoomInt You can select a new center point, and the scales are set to 10. 9:ZoomData This adjusts the Window variables so that all selected statistical plots will be seen. A:ZoomFit Sets a window that shows the maximum and minimum value of Y with with given X window. B:Memory 1:ZoomPrev - restores the window to the previous setting 2:ZoomSto - allows you to store a window 3:ZoomRcl - recalls a stored window C:SetFactors Use this to set the factors by which the calculator zooms in or out.

1:ZoomBox is quite useful when you need to analyze a particular part of a graph without having to reset the window.

Example: Graph the function shown and then use ZoomBox to examine the graph close to the origin.

 Enter the function. Press 4 to graph with ZoomDec. The graph is close to the origin so using ZoomBox will help with the analysis. Press 1 and you will see the window shown here. Use the cursor keys to move the cursor to the indicated point and press . You will see the cursor change to a rectangle. Once you hit , that corner of the box is set and cannot be moved. Now move the cursor to the indicated value. Now press and the graph will be redrawn to show only the part inside the box. Press and scroll to B:Memory and then select 1:ZoomPrev. ZoomPrev restores the graph to the previous window.

2:ZoomIn will zoom in on the graph with the position of the cursor serving as the new center. The default zoom factor is 4, but that can be changed using C:SetFactors.

Example: Use the function from the previous example to ZoomIn.

 Graph the function. Press 2. and you will see the screen at the right. If the cursor is left where it is, the origin will remain the center. Press .

5:ZoomSqr will redraw the graph by adjusting xmin and xmax so that the tick marks are equal in distance on both axes. This is particularly useful when you need to see an accurate shape, such as a circle. ZoomDec is also a square window.

Example: Graph the circle by entering the functions and using ZoomSqr and ZoomStd.

 Enter the functions. Use ZoomStd. Use ZoomSqr.

 Tools Zoom Trace Regraph Math Draw Pen