Exploring Equations of Circles

What are the two most important characteristics of a circle in the coordinate plane?

• Diameter and circumference

• Center and radius

• Area and perimeter

• Slope and y-intercept

What letters represent the center of a circle in its equation?

• (h, k)

• (r, s)

• (x, y)

• (a, b)

How do you determine the center of a circle from its equation?

• By calculating the slope

• By measuring the diameter

• By determining the y-intercept

• By finding the values of h and k

What is the radius of a circle with an equation where the right side equals 4?

• 2

• 4

• 16

• 8

How do you change the signs of h and k when writing the center from an equation?

• Keep the signs the same

• Change plus to minus and vice versa

• Always use positive signs

• Always use negative signs

What is the process to find the radius from an equation of a circle?

• Divide the diameter by 2

• Multiply h and k

• Add h and k

• Square root the right side of the equation

How do you write the equation of a circle given the center (-14, 11) and radius 1?

• x^2 + y^2 = 1

• (x - 14)^2 + (y + 11)^2 = 1

• x^2 + y^2 = 2

• (x + 14)^2 + (y - 11)^2 = 1

What does squaring the radius in the equation of a circle represent?

• The diameter

• The circumference

• The area of the circle

• The right side of the equation

If the center of a circle is at (13, -14) and the radius is the square root of 5, what is the right side of the equation?

• √5

• 10

• 5

• 25

When graphing a circle's equation, what tool can be used to verify correctness?

• Desmos

• A ruler

• A protractor

• A compass