Equations of Circles

Change the following equation to standard form
x²+y²-4x+12y-8=0

• (x+2)²+(y-6)²=48
• (x-2)²+(y+6)²=48
• (x-6)²+(y-2)²=48
• (x+2)²+(y-6)²=48

In the equation (x-3)²+(y+4)²=121, the radius of the circle is

• 242
• 11
• 121
• 22

What is the equation of a circle with radius 2 and center (3, 4)?

• (x+3)² + (y+4)² = 2
• (x-3)² + (y-4)² = 2
• (x+3)² + (y+4)² = 4
• (x-3)² + (y-4)² = 4

What is the equation of a circle with radius 4 and center (0, 8)?

• x² + (y-8)² = 16
• (x-8)² + y² = 4
• x² + (y-8)² = 4
• x² + (y+8)² = 16

Write the standard equation of the circle with the given center and radius; center (0,0) and radius: 3

• x²+y²=3
• x²+y²=6
• x²+y²=9

What is the center of the circle with equation x² + y² = 1?

• (1, 1)
• (0, 0)
• not enough information

What is the equation of a circle with radius 4 and center (0, 8)?

• x² + (y-8)² = 16
• (x-8)² + y² = 4
• x² + (y-8)² = 4
• x² + (y+8)² = 16

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The diameter of a circle has length 12. The center is at (-5, 2). Give the equation of the circle.

• (x - 2)² + (y + 5)² = 36
• (x - 5)² + (y + 2)² = 6
• (x + 5)² + (y - 2)² = 36
• (x + 2)² + (y - 5)² = 6