draw tangent

The line tangent to a curve at a particular point may be drawn while viewing a graph by first pressing         to display TanLn, the tangent line function key.

Press  to place TanLn on the home screen.

Enter the expression in x (such as y1 or sin(x)) or press         to select the function from the list of previously stored functions.

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.

Pressing will display the graph and draw the tangent line.