Heron's Formula

In this program, you'll look at a function that "returns a value". When you call on the function to do a task, it will give you back a result.

Files Needed

What You Should See

A triangle with sides 3,3,3 has an area of 2.0
A triangle with sides 3,4,5 has an area of 6.0
A triangle with sides 7,8,9 has an area of 26.832815729997478
A triangle with sides 5,12,13 has an area of 30.0
A triangle with sides 10,9,11 has an area of 42.42640687119285
A triangle with sides 8,15,17 has an area of 60.0

What You Should Do on Your Own

Assignments turned in without these things will receive no credit.

  1. Compile and run both files (HeronsFormula.java and HeronsFormulaNoFunction.java). Do they both produce the same output? (Answer in a comment in HeronsFormula.java.)
  2. How many lines long is HeronsFormulaNoFunction.java? How many lines long is HeronsFormula.java if you don't count the two lines of comments inside the triangleArea() function? (Put the answers to both questions in a comment in HeronsFormula.java.)
  3. There is a bug in the formula for both files. When (a+b+c) is an odd number, dividing by 2 throws away the .5. Fix both files so that instead of (a+b+c) / 2 you have (a+b+c) / 2.0 everywhere it occurs. Was it easier to fix the file that used a function, or the one that didn't use a function? Answer in a comment.
  4. Add one more test to both files: find the area of a triangle with sides 9, 9, and 9. Was it difficult to add to the file that used a function? Answer in a comment on the line below where you added the new function call.
  5. (You don't need to turn in HeronsFormulaNoFunction.java. Only turn in one file: HeronsFormula.java)

What You Should See After Everything Is Done

A triangle with sides 3,3,3 has an area of 3.897114317029974
A triangle with sides 3,4,5 has an area of 6.0
A triangle with sides 7,8,9 has an area of 26.832815729997478
A triangle with sides 5,12,13 has an area of 30.0
A triangle with sides 10,9,11 has an area of 42.42640687119285
A triangle with sides 8,15,17 has an area of 60.0
A triangle with sides 9,9,9 has an area of 35.074028853269766


©2013 Graham Mitchell

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