Instructions

Write a C$++$program that displays the following menu:

Geometry Calculator

Calculate the Area of a Circle

Calculate the Area of a Rectangle

Calculate the Area of a Triangle

Quit

Enter your choice $(1234)$:

If the user enters $1,$ the program should ask for the radius of the circle then display its area. Use the following formula:

area $=r^2$

Use $3\mathrm{.}14159$ for $$ and the radius of the circle for $r.$

If the user enters $2,$ the program should ask for the length and width of the rectangle, then display the rectangle's area. Use the following formula:

area $=$ length $*$ width

If the user enters $3,$ the program should ask for the length of the triangle's base and its height, then display its area. Use the following formula:

area $=$ base $*$ height $*\mathrm{.}5$

If the user enters $4,$ the program should end.

Input Validation: Display an error message if the user enters a number outside the range of $1$ through $4$ when selecting an item from the menu. Do not accept negative values for the circle's radius, the rectangle's length or width, or the triangle's base or height.