The line tool displays a line segment cursor or a vector cursor on the graph view:
Select the line tool by clicking the button on the graph tools tool bar, or by selecting the 'Line' command from the 'Tools' menu.
When selected, the line tool dialog box is displayed (See below:).
Checking the 'vector' check box changes the line tool into 'vector mode'. When the 'vector' check box is not checked, the line tool is in 'line mode'.
With the 'vector' check box not checked the line tool is in 'line mode' and this dialog box displays the equation of the line and other helpful information. In the screen shot below, the line segment has been captured by the parabola function as its tangent. By moving the mouse left and right, the tangent line travels around the curve.
The line tool dialog box displays:
Press the space bar on the keyboard to plot the equation for the line.
Changing the length and gradient of the line segment:
With the line tool displaying the line segment on the graph view, click and hold the left mouse button while moving the mouse.
With the 'vector' check box checked the line tool is in 'vector mode' and this dialog box displays the 'i' and 'j' components of the vector, the length and direction of the vector, as well as the coordinates of the tail of the vector.
The vector tool dialog box displays: