Identifying Center and Radius from Circle Equations

What is the standard form of a circle's equation?

• h^2 + k^2 = r^2

• x - h^2 + y - k^2 = r^2

• x - h^2 + y - k^2 = r

• x^2 + y^2 = r^2

In the equation of a circle, what do the h and k represent?

• Center coordinates

• Area and perimeter

• Radius and diameter

• Diameter and circumference

If an equation has a '+5' for the y term, what is the y-coordinate of the center?

• Cannot be determined

• 0

• -5

• 5

How do you correctly write the center point from the equation of a circle?

• Divide h and k by 2

• Multiply h and k by 2

• Use the opposite signs of h and k values

• Directly use the h and k values

How do you find the radius from the circle's equation?

• Multiply h and k

• Square root of r^2

• Add h and k

• Square root of r

If the equation of a circle is x - 1^2 + y + 5^2 = 49, what is the center?

• (1, 5)

• (-1, 5)

• (1, -5)

• (-1, -5)

What does the 'r' in the circle's equation stand for?

• Area

• Diameter

• Circumference

• Radius

What mistake do people often make regarding the radius in the circle's equation?

• Adding r to the equation

• Thinking r^2 is the radius

• Forgetting to square root the r^2 value

• Multiplying r by 2

What is the correct way to find the length of the radius from the equation?

• Double the r^2 value

• Square root the r^2 value

• Square the r value

• Use the r value directly

What is the radius of a circle whose equation equals 49?

• 14

• 49

• √49

• 7