Programming your calculator
HERON
Purpose
Uses the lengths of the three sides of a triangle to calculate the area of any triangle, using Heron's formula, known since ancient times.
Operation
Enter the length of each side, followed by 
. Both numbers and expressions (such as √2) are permitted.
The program displays the area of the triangle.
Press 
to enter the side lengths of another triangle.
Test the program by entering sides of a familiar triangle, such as a
Notice what happens when the program is run with side lengths that do not form a triangle (such as
There is a discussion of the use of this sort of program in the text:
Kissane, Barry & Harradine, Anthony (2000) Mathematical Interactions: Measurement,
Chatswood, NSW: Shriro, pp
2
