What is the ratio of any circle's circumference to its radius?

What is the ratio of the diameter and circumference of a circle?

What is the ratio of any circle's circumference to its radius?

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

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

What is the ratio of the diameter and circumference of a circle?

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

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

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

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?