The line tangent to a curve at a particular point may be drawn while viewing a graph by first pressing to display the DRAW menu.
If more than one curve is displayed, use the keys to select the desired curve and enter the x-coordinate of the point where the tangent line is to be drawn.
Press to draw the tangent line.
Observe that the x-coordinate of the point of tangency and the equation of the tangent line (or approximating tangent line) are displayed at the bottom of the screen. Use ClrDraw in the DRAW menu to redraw the graph without the tangent line.
Note: The Tangent command may also be used from the home screen. The instructions are as follows.
From the home screen, select Tangent in the DRAW menu to place Tangent( on the home screen. Enter an expression in x or select the function from the list of previously stored functions in Y-VARS ( ).
The syntax is: Tangent( expression, value ).
value represents the x-coordinate of the point on the curve where the tangent line is to be drawn.
Press to display the graph and the tangent line.