You can use Area Calculator to calculate the areas of shapes.
This is an easy to use, fully functional and good looking application.
You enter the values of your shape, hit calculate and you will be given the area, and the formula; along with the values for each letter in the formula. The interface is very fluid and fast.
The tool to calculate information from the circle is simple; enter just one value and it'll retrieve the other values.
Upon clicking calculate you will be given such information:
Area, formula (and substitutes) and time of the calculation.
This is my first official application and all reviews/downloads help.