Lab 3.1 - Slope Calculator

The slope of a line is equal to the quotent of the rise and the run, which is to say something like (Y2 - Y1) / (X2 - X1). This number is rarely an integer, so it's useful to have a quick and easy way of calculating it.

Create an application that takes the X and Y coordinates of two points on a line and displays the slope in decimal form.

Look! It's a bird! It's a plane! It's an object list!

• Four Text Boxes: one each for the X1 and Y1 coordinates, and the X2 and Y2 coordinates. Make sure each has a Label so the user knows what they are.
• A Button to do the calculations. Take the values from the Text Boxes and plug them into the formula.
• A Label to display the results (with a Label to indicate that it's for the results).

WARNING: Remember that a vertical line (one where both points' X-coordinates are the same) has no slope. The computer will give you a bad answer if it tries to divide by zero, so make sure your program checks for that before telling it to divide by (X2 - X1); the computer will have to make a decision about whether it can do the division before actually doing it. If your answer is "NaN" or "Infinity" or "-Infinity" then you're doing it wrong. Do not allow the computer to divide by zero, even if VB translates the answer into something it can understand.

Here's sample data and answers that you should get:

X1	Y1	X2	Y2	Result
8	6	12	18	3
-3	5	85	-4.2	-0.10454545454545
6	5	6	-4.2	Undefined

Common mistakes include:
• Not setting the TextAlign property to Right in TextBoxes intended for numeric input.
• Not checking the input to avoid dividing by zero.
• Losing track of which TextBox goes with which variable.
• Losing track of which Label goes with which TextBox.
• Using global scope when you should be using local scope.
• Letting the computer divide by zero at any point.
• Not leaving enough space to display the full result.
• Wasting real estate or cutting off the title of the program.

OPTION: Come up with a method to also display the answer as a fraction. The fraction must be an improper fraction in lowest terms. Five tokens to the first player who figures it out.

As always, design a useful and proper interface.