[list=1][*]Add a [b]Slider[/b] and name it [b]m[/b].[br][br][/*][*]Add a [b]Slider[/b] and name it [b]c[/b].[br][br][/*][*]In the input bar type [b]y=m*x+c [/b]and press enter.[br][br][/*][*]Add a [b]New Point[/b], A,[b] [/b](2[sup]nd [/sup]button) on the line (the cursor should change as you hover over [br]the line).[br][br][/*][*]Add another [b]New Point[/b] on the line, B.[br][br][/*][*]Use [b]Perpendicular Line[/b] (4[sup]th [/sup]button) to construct a perpendicular to the [i]y[/i]-axis[br]through A.[br][br][/*][*]Use [b]Perpendicular Line[/b] (4[sup]th [/sup]button) to construct a perpendicular to the [i]x[/i]-axis[br]through B.[br][br][/*][*]Use [b]Intersect Two Objects [/b](2[sup]nd[/sup] set of buttons) to find [br]the intersection of the perpendicular lines, C.  You can also hide the perpendicular lines by clicking on the blue circles next to their names in the Algebra view.[br][br][/*][*]Use [b]Segment [/b](3[sup]rd[/sup] set of buttons) to add the segment AC.[br][br][/*][*]Use [b]Segment [/b](3[sup]rd[/sup] set of buttons) to add the segment BC.  By selecting each of the segments in turn and use the Graphics Style Bar to change the colour and display the value.[br][br][/*][*]Use [b]Insert Text [/b](10[sup]th[/sup]menu) to add a text-box.  Enter  [b]f=m×e[/b]. [br][b]e[/b],[b] f [/b]and [b]m[/b] can be selected from the Advanced/Objects menu.[br][br][/*][*]Use [b]Insert Text [/b](10[sup]th[/sup]menu) to add a text-box.  Enter  [b]a[/b] (from the Advanced/Objects menu).  The text should be formatted as a LaTeX formula.[br][/*][/list]