Two legs of a right triangle measure 3 and 4, respectively. What is the area of the circle that circumscribes the triangle?

The perimeter of a circle is 36 π. What is the diameter of the circle?

If the area of the circle touching the square in the picture above is , what is the closest value to the area of the square?

What is the diameter of a circle with a circumference of ?

If the area of a circle is four times larger than the circumference of that same circle, what is the diameter of the circle?