Application Guide

77 Graphs Application
Note: The default tolerance for detecting parallel/perpendicular lines is 12.5
degrees. This tolerance can be redefined using a variable named
ti_gg_fd.angle_tol. You can change the tolerance in the current problem by setting
this variable in the calculator app to a value in the range 0 through 45 (0=no
parallel/perpendicular detection).
Drawing Circles and Ellipses
To create a circle or ellipse, use the touchscreen to draw the approximate shape.
• If the drawn shape is sufficiently circular, a circle is created.
• If the shape is elongated, an ellipse is created.
• If the virtual center of the drawn shape is near an existing point, the circle or
ellipse is centered on that point.
Drawing Triangles
To create a triangle, draw a triangle-like shape.
• If a drawn vertex is close to an existing point, the vertex snaps to the point.
Drawing Rectangles and Squares
To create a rectangle or square, use the touchscreen to draw the perimeter.
• If the drawn shape is nearly square, a square is created.
• If the drawn shape is elongated, a rectangle is created.
• If the center of a square is close to an existing point, the square snaps to that
point.
Drawing Polygons
To create a polygon, tap a succession of existing points, ending on the first point you
tapped.
Using MathDraw to Create Equations
In the Graphs view, MathDraw attempts to recognize certain gestures as functions for
analytic parabolas.