In a JavaFX application there is a TextField control(tfRadius)
for taking input of a circle's radius. A respective square whose
diagonal is the circle's diameter can then be created. There are
three other controls in this application: a button(btCalculate),
two textareas(trCircleArea, trSquareArea). When the button is
clicked, the circle's area is calculated and displayed on
trCircleArea, furthermore, the square's area is also calculated and
displayed on trSquareArea.
Please write portions of codes which calculates the circle's
area and the square's...