GeoMaster on the TI-84 Plus graphing calculator can find the area of any circle, triangle, or simple polygon constructed using the Circle, Triangle, Polygon, or RegPolygon tool in the DRAW menu. A polygon is simple if its sides intersect only at the vertices of the polygon. In addition, GeoMaster is also not capable of directly finding the area of a polygon formed by the intersection of two other polygons.

To find the area of a circle, triangle, or simple polygon constructed using the tools in the DRAW menu, follow these steps:

  1. Press [GRAPH][ZOOM][2] to select the Area tool.

    The name of the tool appears in the upper-right corner of the screen.

  2. Use the Arrow keys to move the cursor to the object whose area you want to find, and then press [ENTER] to select that object.

    The object is displayed using dashed lines and the requested area appears on the screen.

    If you don’t like GeoMaster’s placement of the area, before performing the next step, you can use the arrow keys to relocate it.

  3. Press [ENTER] to anchor the placement of the area measurement.

  4. To find the area of another object, repeat Steps 2 and 3.

  5. When you are finished finding areas, press [ENTER] again or move the cursor away from the last object. To deactivate the Area tool, press [ENTER] or select another menu item.

    After pressing [ENTER], all objects are displayed using solid lines.