What is the diameter of the circle with the equation x^2 + y^2 =25 ? Geometry 1 Answer NJ Feb 27, 2018 10 Explanation: #x^2+y^2 = r^2# is the equation of a circle. #r# is the radius of the circle. The equation given corresponds to #r=5#. Since the diameter is twice the radius, the diameter is 10. Answer link Related questions How do I determine the molecular shape of a molecule? What is the lewis structure for co2? What is the lewis structure for hcn? How is vsepr used to classify molecules? What are the units used for the ideal gas law? How does Charle's law relate to breathing? What is the ideal gas law constant? How do you calculate the ideal gas law constant? How do you find density in the ideal gas law? Does ideal gas law apply to liquids? Impact of this question 4020 views around the world You can reuse this answer Creative Commons License