Equation of a Circle

• What would be the radius of a circle with the equation below?

  Radius = 3.5

  
• Would the points below be inside, outside or on the circumference of the circle?

  a - Outside , b - Inside , c - On the circumference

  
• The point (3,4) lies on the circumference of a circle centre (0,0). Work out the equation of the Circle? (The equation of a circle is x² + y² = r²)

  x² + y² = 25
• Work out the radius of a circle with the equation below

  Radius = 2.5

  
• Work out the radius of a circle that has the equation below

  Radius = 4.5