Equation of a Circle Investigation

Topic:
Circle
Investigation into circles
What is the equation of a circle with: Radius 1 centre the origin- Radius 2 centre the origin- Radius 3 centre the origin- Radius 4 centre the origin- Radius 5 centre the origin- Radius r centre the origin- Radius 2 centre (1, 0)- Radius 3 centre (1, 2)- Radius 4 centre (2, 3)- Radius 5 centre (-2, -1)- What is the equation of a circle with Radius r centre the origin. What can you say about the relationship (x-a)^2+(y-b)^2=r^2 ? Describe what the following equations represent. x^2+y^2=9 x^2+y^2-25=0 (x-2)^2+y^2=9 (x+2)^2+(y-3)^2=9