12.4-12.4 Review

What is the standard equation of a circle?

• (x-k)² + (y-h)² = r²

• (x+h)² + (y+k)² = r²

• (x-h)² + (y-k)² = r²

• (k-x)² + (h-y)² = r²

What does (h,k) standard for in the standard circle equation?

• (h,k) is the center of the circle

• (h,k) is a point on the circle.

• (h,k) is a point that we guess and find

• (h,k) is the distance of the circle

What is the center and the radius of the circle with equation, (x-4)² + (y-2)² = 25

• Center is (5,2) and radius is 4.

• Center is (2,5) and radius is 4

• Center is (2,4) and radius is 5

• Center is (4, 2) and radius is 5

What is the center and radius of a circle with the equation, (x-1)² + (y-3)² = 4

• Center is (1,3) and radius is 2

• Center is (3,1) and radius is 2

• Center is (3,2) and radius is 1

• Center is (2,3) and radius is 1

What is the circle equation, given the center is (4,1) and the radius is 3?

• (x-4)² + (y-1)² = 9

• (x+4)² + (y+1)² = 9

• (x+1)² + (y+4)² = 9

• (x-1)² + (y-4)² = 9

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

• (x+2)² + (y-3)² = 2

• (x-2)² + (y+3)² = 16

• (x+2)² + (y-3)² = 16

• (x-2)² + (y-3)² = 2

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

A circle has the equation  
x² + y² - 12x + 8y + 3 = 0.  Write the equation in standard form.

• (x - 6)² + (y + 4)² = 49
• (x + 4)² + (y - 6)² = 49
• (x - 6)² + (y + 4)² = 55
• x² + y² = 55

In the circle represented by the equation (x-4)²+(y-3)²=25, the diameter is

• 10

• 3

• 5

• 25

What is the value of y? Round to the nearest whole number.

• 16
• 17
• 18
• 19