Write a QBASIC program that calculates the area of a circle, a rectangle and a triangle. The program should allow the user to select the shape (C or c for circle, R or r for Rectangle, T or t for Triangle) whose area he or she wants calculated. It should then accept the dimensions of the shape, and calculate and print the area . The table below details the formula and dimensions to use for each of the shapes.

area of a circle

write a QBASIC to find the area of circle

Sure, I can help you with that. Here's a QBASIC program that does what you described:

```qbasic
CLS
PRINT "Shape Area Calculator"
PRINT "---------------------"
PRINT "C - Circle"
PRINT "R - Rectangle"
PRINT "T - Triangle"
PRINT "---------------------"
PRINT "Enter the shape (C, R or T): ";
INPUT shape

IF shape = "C" OR shape = "c" THEN
PRINT "Enter the radius of the circle: ";
INPUT radius
area = 3.14159 * radius * radius
PRINT "The area of the circle is: "; area
ELSEIF shape = "R" OR shape = "r" THEN
PRINT "Enter the length of the rectangle: ";
INPUT length
PRINT "Enter the width of the rectangle: ";
INPUT width
area = length * width
PRINT "The area of the rectangle is: "; area
ELSEIF shape = "T" OR shape = "t" THEN
PRINT "Enter the base of the triangle: ";
INPUT base
PRINT "Enter the height of the triangle: ";
INPUT height
area = 0.5 * base * height
PRINT "The area of the triangle is: "; area
ELSE
PRINT "Invalid input. Please enter C, R or T."
END IF

END
```

To run this program, you can use a QBASIC interpreter, such as QB64 or QBASIC for DOS. Simply copy and paste the code into the editor, save the file with a `.bas` extension, and run it.

When the program is executed, it displays a menu asking the user to select a shape. Based on the user's input, it asks for the dimensions of the shape and calculates the area using the appropriate formula. Finally, it prints the calculated area.

Note that the formulas used for each shape are as follows:

- Circle: Area = π * radius^2
- Rectangle: Area = length * width
- Triangle: Area = 0.5 * base * height

You can customize or modify the program further based on your specific requirements.

Very poor answer