How would I find the diameter of a circle when area is given? Geometry Perimeter, Area, and Volume Circumference and Area of Circles 1 Answer sente Dec 24, 2015 #d = 2sqrt(A/pi)# Explanation: The area #A# of a circle is given by #A = pi r^2# where #r# is the radius of the circle. But the radius is half the diameter, so if the diameter of the circle is #d#, we have #A = pi(d/2)^2# #=> A= pid^2/4# #=>4/piA = d^2# #=> sqrt(4/piA) = d# Thus we have the diameter #d# as #d = 2sqrt(A/pi)# Answer link Related questions What is the circumference of a 15-inch circle if the diameter of a circle is directly... If the radius of a circle is 4cm, what is the area? How do you find the circumference of a circle with a diameter of 6 cm? How much will it cost to paint a circular sign with a radius of 4 feet if the painter charges... What is the circumference of a circle with a radius of 30 inches? Write the equation of a circle with a center at (-3,-4) and a radius of 3? What is the perimeter of a quadrant of a circle with radius 3cm? I am installing a 1 yard-wide walk around circular swimming pool that is 21 ft in diameter. What... What is the circumference of a circle with radius of 30 inches? What is the equation of a circle with a center at (-3, -4) and a radius of 3? See all questions in Circumference and Area of Circles Impact of this question 1782 views around the world You can reuse this answer Creative Commons License