In this instructable, I will show you how to write a program on your calculator that will do Heron's formula for you.

This is a link to my Quadratic formula program instructable.  You will probably find this instructable helpful too.

## Step 1: Getting Started

First, you push the program button.  Then push the right arrow twice and hit enter.  Now enter a name using the alpha key (the green one).  When you finish entering a name, hit enter.

## Step 2: Writing the Program

Look at the pictures below and enter that info on you calculator.  To get Prompt,  press program, the right arrow, then 2.  Then enter  A,B,C.  make sure that you put the commas in there.
Now hit enter to go to the next line and write  (A+B+C)/2->S.  This way, you don't even have to find out what the semiperimeter is.  To get the arrow symbol, push the STO-> button (right above the ON button).

## Step 3: The Equation

symbol. Ifin the equation.  Press 2nd, x^2 to get the square root symbol.
If you want to be able know what the answer is before finding the square root of it, then write the same thing again but without the square root. Also, make sure you press STO, Y not X.

## Step 4: The Last Bit

To get Disp, press program then the right arrow, then 3.  Now open quotes (alpha, +).  To make spelling faster, press 2nd, alpha.  Now type THE AREA IS:  .  To get the colon, press alpha, then the decimal button.  Make sure you close quotes.
Now press comma, open quotes, eleven spaces (alpha, 0) put in the square root symbol, close quotes.  Finish it off with ,Y,X.  Look at the picture below to see what it should look like.

## Step 5: Putting It to Use

Now press 2nd, mode (quit) to exit out of the editing screen.  Press program, then select the one you just made (press enter).  When prgmHeron press enter the input the values of A, B, C then hit enter.  In the picture below, I took a simple 3,4,5 right triangle.  One half of three times four is 6.  We know that the area is 6 and the program says the same.  Now try it on your new program!
<p>This was pretty straightforward, I found it easier to follow than the quadratic equations solution. Thanks so much~!</p>
I tried it on a casio CFX-9850G and it worked, You are awesome !!
just as an improv, you could do :Output(4,12,&quot;&radic;&quot;<br />
That's a great idea! I will update this one and my other instructible soon. Thanks!