The line tangent to a curve at a particular point may be drawn while viewing a graph by first pressing .
Select the Tangent function by pressing or scroll down to A:Tangent and press .
If more than one curve is displayed, use the keys to select the desired curve. Enter the x-coordinate (or trace the curve to the approximate point) where the tangent line is to be drawn.
Press to draw the tangent line.
The equation of the tangent line (or the approximating tangent line) is displayed at the bottom of the screen. Use CLDRW in the DRAW menu to redraw the graph without the tangent line.
Note: The number of decimal places shown can be changed in the MODE menu.