Question: how to find the circumference of a circle inscribed in a square?
Answer: Find formulas for the circle's radius, diameter, circumference and area , in terms of 'a'. As we've shown above, the circle's radius is equal to the half the length of the square's side, so r=a/2. The diameter is twice the radius, so d=a. The circumference is d ·π, so C=πa.